1. Why active directory not asking for os setup(server). when we install the active directory?

Active directory is a centralized data base, group of servers, computer, user are common NTDS base this used in organization. Or company.

This not for OS level, its microsoft based its like installed tool server manager ADDS and Mondaory for DNS.

2. What is the use of ping command?

by using the ping command we can know wether our network is dead or alive..........

3. What is patch management?

Patch management is an area of systems management that involves acquiring, testing, and installing multiple patches (code changes) to an administered computer system. Patch management tasks include: maintaining current knowledge of available patches, deciding what patches are appropriate for particular systems, ensuring that patches are installed properly, testing systems after installation, and documenting all associated procedures, such as specific configurations required. A number of products are available to automate patch management tasks, including Ringmaster's Automated Patch Management, Patch Link Update, and Gibraltar's Ever guard

4. What is difference between TCP/IP and UDP?

TCP - Transfer Control Protocol.

* a. Reliable
* b.Connection oriented.
* c.Acknowledgement

UDP - User Datagram Protocol.

* a.Non Reliable
* b.Connectionless
* c.No Acknowledgement

5. What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

6. What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.

7. What is SLIP (Serial Line Interface Protocol)?

It is a very simple protocol used for transmission of IP datagrams across a serial line.

8. What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

9. What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.

10. What is EGP (Exterior Gateway Protocol)?

It is the protocol the routers in neighboring autonomous systems. It is used to identify the set of networks that can be reached within or via each autonomous system.

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11. What are NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications. NETBEUI is NetBIOS extended user interface. A transport protocol designed by Microsoft and IBM is for the use on small subnets.

12. What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

13. What is redirector?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

14. Define GSM Technology

GSM is a short-range wireless technology and is usually used in the mobile phones, hand help devices, MP3 players, Laptops, computers and in cars.

15. What is a Frame Relay?

Frame relay is high-speed data communication technology that operates at the physical and data link layers of the OSI model. Frame relay uses frames for data transmission in a network.

16. What is a RAS server?

RAS or remote access server allows you to remote dial in through the desktop computers, laptops, and GSM mobile phones.

17. Define Bluetooth Technology

Bluetooth is a short-range wireless technology that uses radio waves for communication. Many mobile phones, laptops, MP3 players have built in features of the Bluetooth.

18. What is VOIP?

VOIP or voice over internet protocol is a technology that uses IP based networks such as internet or private networks to transmit the voice communication.

19. What is Virtual Private Network (VPN) and how does it work?

VPN or virtual private network is used to connect two networks by means internet. VPN uses PPTP (point-to-point tunneling protocol) and other security procedures to make a secure tunnel on internet.

20. What is UDP?

UDP or user datagram protocol is a connectionless protocol that is used to transfer the data without any error handling.

21. What are the standard port numbers for SMTP, POP3, IMAP4, RPC, LDAP, and FTP?

SMTP - 25, POP3 - 110, IMAP4 - 143, RPC - 135, LDAP, FTP-21, HTTP-80

22. What is LDAP?

Lightweight Directory Access Protocol is used to access the directory services from the Active directory in Windows operation systems.

23. Name the Seven Layers of OSI Model

The seven layers of the OSI are Application, Presentation, Sessions, Transport, Network, Data Link, and Physical layer.

24. What is WiMax?

WiFi is a next form of the WiFi. WiMax is a high-speed broadband network technology that is designed for the corporate offices, roaming and home users.

25. What is WiFi?

WiFi or wireless fidelity is a base-band network technology that is used for the wireless data communication.

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26. What is an IP Address?

An IP address is a unique identifier of a computer or network device on the local area network, WAN or on internet. Every host computer on the internet must have a unique IP address. IP addresses on the internet are usually assigned by the local ISPs to which users are connected.

27. What is Subnet Mask?

A subnet mask is used to determine the number of networks and the number of host computers. Every class of the IP address uses the different range of the subnet mask. Subnet masks allow the IP based networks to be divided into the sub networks for performance and security purposes.

28. What is WLAN?

WLAN or Wireless local area network is simply a type of network that does not use wired Ethernet connections for networking. WLAN uses wireless network devices such as wireless routers etc.

29. What is Gateway?

A gateway is software or a hardware that is used to connect the local area network with the internet. A gateway is a network entrance point and a router usually works as a gateway.

30. What is DHCP?

Dynamic host configuration protocol is used to assign the IP address to the networked computers and devices. DHCP is a network protocol that automatically assigns static and dynamic IP addresses from its own range.

31. What is DNS?

Domain name system/server is used to translate the IP address into the hostname and hostname into the IP address. DNS is mostly used on the internet and the networks.

32. What is the difference between the communication and transmission?

Transmission is a physical movement of information and concern issues like bit polarity, synchronization, clock etc. Communication means the meaning full exchange of information between two communication media.

33. Explain point-to-point protocol

A communications protocol used to connect computers to remote networking services including Internet service providers.

34. Explain difference between base band and broadband transmission

In a base band transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.

35. Explain Protocol Data Unit

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is an information frame (I - frame) or a supervisory frame (S - frame) or anunnumbered frame (U - frame).

36. What are major types of networks and explain

Server-based networkPeer-to-peer networkPeer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration

37. Explain passive topology

When the computers on the network simply listen and receive the signal, they are referred to as passive because they do not amplify the signal in any way. Example - linear bus

38. Explain mesh network

A network in which there are multiple networks links between computers to provide multiple paths for data to travel.

39. What are the different types of networking / internetworking devices?

Repeater: Also called a regenerator, an electronic device operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.Bridges: These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipient and control congestion.Routers: They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enables them to determine which of the several possible paths the best for a particular transmission is.Gateways: They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.

40. How Gateway is different from Routers

A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats.

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41. Explain Brouter

This is a Hybrid device combines the features of both bridges and routers.

42. Explain subnet

A generic term for section of a large networks usually separated by a bridge or router.

43. Explain SAP

Series of interface points that allow other computers to communicate with the other layers of network protocol stack.

44. Explain frame relay, in which layer it comes

Frame relay is a packet switching technology. It will operate in the data link layer.

45. Explain terminal emulation, in which layer it comes

Telnet is also called as terminal emulation. It belongs to application layer.

46. Explain Beaconing

This process allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.

47. Explain redirector

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

48. Explain NETBIOS and NETBEUI

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications. NETBEUI is NetBIOS extended user interface. A transport protocol designed by Microsoft and IBM can be used on small subnets.

49. Explain RAID

This is a method for providing fault tolerance by using multiple hard disk drives.

50. Explain cladding

Cladding is a layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.

51. Explain attenuation

The degeneration of a signal over distance on a network cable is called attenuation.

52. Explain MAC address

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

53. What is the difference between bit rate and baud rate?

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits. Baud rate = bit rate / N where N is no-of-bits represented by each signal shift.

54. Explain Bandwidth

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.

55. Explain Project 802

It is a project started by IEEE to set standards. It enables intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of major LAN protocols.It consists of the following:

802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols. 802.2 Logical link control (LLC) is the upper sub layer of the data link layer, which is non-architecture-specific, that is, remains the same for all IEEE-defined LANs. Media access control (MAC) is the lower sub layer of the data link layer that contains some distinct modules. Each one carries proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5). 802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.

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56. What are the data units at different layers of the TCP / IP protocol suite?

The data unit created at the application layer is called a message; at the transport layer, the data unit created is called either a segment or a user datagram. At the network layer, the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.

57. Explain ICMP

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

58. Explain difference between ARP and RARP

The address resolution protocol (ARP) is used to associate the 32-bit IP address with the 48-bit physical address, used by a host or a router to find the physical address of another host on its network by sending an ARP query packet that includes the IP address of the receiver. The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

59. Explain the minimum and maximum length of the header in the TCP segment and IP datagram

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

60. Explain the range of addresses in the classes of internet addresses

Class A 0.0.0.0 - 127.255.255.255Class B 128.0.0.0 - 191.255.255.255Class C 192.0.0.0 - 223.255.255.255Class D 224.0.0.0 - 239.255.255.255Class E 240.0.0.0 - 247.255.255.255

61. Explain the difference between TFTP and FTP application layer protocols

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offered by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer, and another for control information.

62. What is 5-4-3 rule?

In an Ethernet network, between any two points on the network, there can be no more than five network segments or four repeaters and of those five segments, only three of segments can be populated.

63. Explain MAU

In token Ring, hub is called Multistate Access Unit (MAU).

64. Explain the difference between routable and non- routable protocols

Routable protocols can work with a router. It can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router

65. Explain logical link control

One of two sub layers of the data link layer (of OSI reference model), as defined by the IEEE 802 standard. This sub layer is responsible for maintaining the link between computers when they are sending data across the physical network connection.

66. Explain virtual channel

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

67. Explain virtual path

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.

68. Explain packet filter

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

69. Explain traffic shaping

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

70. Explain multicast routing

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.

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71. Explain region

When hierarchical routing is used, the routers are divided into what we call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

72. Explain silly window syndrome

This problem can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.

73. Explain wide-mouth frog

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

74. Explain Mail Gateway

A system performs a protocol translation between different electronic mail delivery protocols.

75. Explain IGP (Interior Gateway Protocol)

It is any routing protocol used within an autonomous system.

76. Explain EGP (Exterior Gateway Protocol)

It is the protocol routers in neighboring autonomous systems. It is used to identify the set of networks that can be reached within or via each autonomous system.

77. Explain autonomous system

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.

78. Explain BGP (Border Gateway Protocol)

This is a protocol, which is used to advertise the set of networks. This can be reached within an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).

79. Explain Gateway-to-Gateway protocol

It is a protocol formerly used to exchange routing information between Internet core routers.

80. Explain NVT (Network Virtual Terminal)

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

81. Explain a Multi-homed Host

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.

82. Explain Kerberos

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

83. Explain Proxy ARP

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

84. Explain OSPF

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.

85. Explain SLIP (Serial Line Interface Protocol)

It is a very simple protocol. It is used for the transmission of IP datagram's across a serial line.

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86. Explain RIP (Routing Information Protocol)

It is a simple protocol used to exchange information between the routers.

87. Explain source route

It is the sequence of IP address to identify the route a datagram must follow source route may optionally be included in an IP datagram header.

88. What are the advantages and disadvantages of the three types of routing tables?

The three types of routing tables are fixed, dynamic, and fixed central. The fixed table must be manually modified every time there is a change. A dynamic table changes its information based on network traffic, reducing the amount of manual maintenance. A fixed central table lets a manager modify only one table, which is then read by other devices. The fixed central table reduces the need to update each machine's table, as with the fixed table. Usually a dynamic table causes the fewest problems for a network administrator, although the table's contents can change without the administrator being aware of the change.

89. What is HELLO protocol?

The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.

90. Explain the difference between interior and exterior neighbor gateways

Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside world.

91. What protocol do DNS name servers use?

DNS uses UDP for communication between servers. It is a better choice than TCP because of the improved speed a connectionless protocol offers. Of course, transmission reliability suffers with UDP.

92. Explain a DNS resource record

A resource record is an entry in a name server's database. There are several types of resource records, used including name-to-address and resolution information. Resource records are maintained as ASCII files.

93. Explain External Data Representation

External Data Representation is a method of encoding data within an RPC message, used to ensure that the data is notsystem-dependent.

BOOTP helps a diskless workstation boot. How does it get a message to the network looking for its IP address and the location of its operating system boot files?

BOOTP sends a UDP message with a sub network broadcast address and waits for a reply from a server that gives it the IP address. The same message might contain the name of the machine that has the boot files on it. If the boot image location is not specified, the workstation sends another UDP message to query the server.

94. Explain REX

What advantage does REX offer other similar utilities?

95. Explain a pseudo TTY

A pseudo TTY or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo TTY, noconnection can take place.

96. Explain anonymous FTP and why would you use it

Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user's ID for tracking purposes only. Anonymous FTP is used to enable a large number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access.

97. Explain a Management Information Base (MIB)

A Management Information Base is part of every SNMP-managed device. Each SNMP agent has the MIB database thatcontains information about the device's status, itsperformance, connections, and configuration. The MIB is queried by SNMP.

98. Explain the difference between an unspecified passive open and a fully specified passive open

An unspecified passive open has the server waiting for a connection request from a client. A fully specified passive open has the server waiting for a connection from a specific client.

99. What is FTP?

FTP is short for File Transfer Protocol. This is the protocol used for file transfer over the Internet.

100. What can you suggest to enhance testing process on windows OS?

Put shortcut to notepad.exe in Send to folder. It is speed up work with different files like hosts, configuration files.

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101. What do you need to do that your browser will point URL www.YourTest.com to the internal IP address 127.99.11.01?

Make changes in the hosts file in C:WINDOWSsystem32driversetc the Hosts file is looked at first before going out to the DNS (Domain Name Service) servers. You have to put the following on new lines at the end of hosts file: 127.99.11.01 YourTest.com 127.99.11.01 www.YourTest.com

102. How to determine whether there is an issue with the DNS configuration of your connection to your ISP?

At a command prompt, type ipconfig /all, and then press ENTER to display the IP address of your DNS server. If the IP address for your DNS server does not appear, you need contact your ISP.

103. How do you start DirectX Diagnostic Tool?

To start the DirectX Diagnostic Tool: 1. Click Start, and then click Run. In the Open box, type dxdiag, and then click OK.

104. How to find what program used as default for opening file .xyz

In cmd type C :> assoc .xyz which program will open that .xyz file

The first thing you will want to do is Start, Run, cmd.exe, then right click the window menu and choose properties. Try the following values for improvement: Options | Command History | Buffer Size | 400 Options | Command History | Discard Old Duplicates | True Options | Edit Options | Quick Edit Mode | True Layout | Screen buffer size | Height | 900 Layout | Window size | Height | 40

105. How do we find a network configuration of your PC?

In cmd type c :> net config workstation the result displays a list of configurable services: computer name, user name, logon domain, domain DNS name.

106. What is the port number of the service to use for the connection?

The default is 23 (TELNET service).

107. What is telnet?

Telnet is a text based communication program that allows you to connect to a remote server over a network. Telnet is the name or IP address of the remote server to connect.

108. How do we find what ports are open on your system?

In cmd type c :> netstat this command gives you a generic look at what ports are open on your system

109. How to find a path on the network from your PC that is running load test script to web server?

Use Tracert Utility runs at the Command prompt. It will trace a path from you to the URL or IP address given along with the tracert command. Tracert determines the route taken to a destination by sending ICMP echo packets

110. How do we to verify connection to remote computer?

Ping tool verifies connections to remote computers example: In cmd type c :> ping 192.168.0.1 -t -t Ping the specified host until interrupted -a Resolve addresses to hostnames

111. How do we find IP address of your connection?

Go to start/run type 'cmd' then type 'ipconfig' Add the '/all' switch for more info.

112. How do we open the command prompt?

To open a command prompt window in Windows 2000 or XP, click on "Start | Run", type cmd in the box, and click OK.

113. List out the benefits obtained by using the Client/Server oriented TP Monitors

# Client/Server applications development framework

# Firewalls of protection

# High availability

# Load balancing

# MOM integration

# Scalability of functions

# Reduced system cost

114. What is Client/Server?

Clients and Servers are separate logical entities that work together over a network to accomplish a task. Many systems with very different architectures that are connected together are also called Client/Server.

115. What are the five major technologies that can be used to create Client/Server applications?

# Database Servers

# TP Monitors

# Groupware

# Distributed Objects

# Intranets

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116. hat is Load balancing?

If the number of incoming clients requests exceeds the number of processes in a server class, the TP Monitor may dynamically start new ones, and this is called Load balancing.

117. What is meant by Asymmetric Multiprocessing (AMP)?

It imposes hierarchy and a division of labor among processors. Only one designated processor, the master, controls (in a tightly coupled arrangement) slave processors dedicated to specific functions.

118. What is General Middleware?

It includes the communication stacks, distributed directories, authentication services, network time, RPC, Queuing services along with the network OS extensions such as the distributed file, and print services.

119. What is meant by Symmetric Multiprocessing (SMP)?

It treats all processors as equal. Any processor can do the work of any other processor. Applications are divided into threads that can run concurrently on any available processor. Any processor in the pool can run the OS kernel and execute user-written threads.

120. What does Middleware mean?

Middleware is distributed software needed to support interaction between clients and servers. In short, the software is in the middle of the Client/Server systems. In addition, it acts as a bridge between the clients and servers. It starts with the API set on the client side that is used to invoke a service and it covers the transmission of the request over the network and the resulting response.It neither includes the software that provides the actual service - that is in the server's domain nor the user interface or the application login - that is in client's domain.

121. What is Message Oriented Middleware (MOM)?

MOM allows general-purpose messages to be exchanged in a Client/Server system using message queues. Applications communicate over networks by simply putting messages in the queues and getting messages from queues. It typically provides a very simple high level APIs to its services.

MOM's messaging and queuing allow clients and servers to communicate across a network without being linked by a private, dedicated, logical connection. The clients and server can run at different times. It is a post-office like metaphor.

122. What is the Classification of clients?

Non-GUI clients - Two types are-

1. Non-GUI clients that do not need multi-tasking(Example: Automatic Teller Machines (ATM), Cell phone)
2. Non-GUI clients that need multi-tasking(Example: ROBOTs)GUI clientsOOUI clients

123. What are the main components of Transaction-based Systems?

# Resource Manager

# Transaction Manager and

# Application Program

124. What is Remote Procedure Call (RPC)?

RPC hides the intricacies of the network by using the ordinary procedure call mechanism familiar to every programmer. A client process calls a function on a remote server and suspends itself until it gets back the results. Parameters are passed like in any ordinary procedure. The RPC, like an ordinary procedure, is synchronous. The process that issues the call waits until it gets the results.

Under the covers, the RPC run-time software collects values for the parameters, forms a message, and sends it to the remote server. The server receives the request, unpacks the parameters, calls the procedures, and sends the reply back to the client. It is a telephone-like metaphor.

125. What are the characteristics of Client/Server?

# Service

# Shared resources

# Asymmetrical protocols

# Transparency of location

# Mix-and-match

# Message based exchanges

# Encapsulation of services

# Scalability

# Integrity

Client/Server computing is the ultimate "Open platform". It gives the freedom to mix-and-match components of almost any level. Clients and servers are loosely coupled systems that interact through a message-passing mechanism.

126. What is Structured Query Language (SQL)?

SQL is a powerful set-oriented language, which was developed by IBM research for the databases that adhere to the relational model. It consists of a short list of powerful, yet highly flexible, commands that can be used to manipulate information collected in tables. Through SQL, we can manipulate and control sets of records at a time.

127. Explain the building blocks of Client/Server.

The client side building block runs the client side of the application.The server side building block runs the server side of the application.

The middleware building block runs on both the client and server sides of an application. It is broken into three categories:-

# Transport stack

# Network OS

# Service-specific middleware

128. What are the building blocks of Client/Server?

The client

# The server and

# Middleware

129. TP Monitor does mainly two things extremely well. They are Process management and Transaction management.

They were originally introduced to run classes of applications that could service hundreds and sometimes thousands of clients. TP Monitors provide an OS - on top of existing OS - that connects in real time these thousands of humans with a pool of shared server processes.

130. What are the most typical functional units of the Client/Server applications?

User interface

# Business Logic and

# Shared data

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131. What is patch panel? What is the use?

A panel of network ports contained together, usually within a telecommunications closet that connects incoming and outgoing lines of a LAN or other communication, electronic or electrical system. In a LAN, the patch panel connects the network's computers to each other and to the outside lines that enable the LAN to connect to the Internet or another WAN. Connections are made with patch cords. The patch panel allows circuits to be arranged and rearranged by plugging and unplugging the patch cords.

132. What is uplink?

It is the technical term for data transmission in the direction from the subscriber to the network. Or rather, back to the provider or Internet provider. It is called as back channel. The opposite transmission direction, the 'transmission channel', is called the 'uplink' in technical jargon.

133. Why does blue screen of death occur while installing the windows XP or any other OS installation?

This situation occurs when the minimum hardware requirements of OS is not sufficient then blue screen appears.

134. What are the services primitives present in CN?

1. Request
2. Indication
3. Response
4. Confirmation

135. How do you check the listening ports on a windows box Command line?

Netstat-a : displays IP, listening port idsNetstat /? : help

136. What is the command to start a service in Windows from command line?

Start-Run-Type CMD -- Then type below command in commandPrompt Net stop <service name> Net start "<service>"

137. What is the TCP/IP protocol number?

IP number is a data transfer and without IP number, not any handle data and without tcp not transfer the data. In addition, not reached the data will not transfer.

138. What is active Directory? What is main role in windows 2003 server?

Active directory is the main part of 2003 server. The active directory installing the computer all hosts provide rooming service. In addition, user all information contain in the active directory.

139. What is modem and what use of in networking?

Modem is modulator demodulator modulator converts bits transferred into electrical pulses demodulator converts electrical pulses into bits. It is very useful in networking when we r using internet.

140. Explain hidden sharing and open sharing. How can we assign that?

In windows OS family, Right click on My Computer--> manage --> shared Folders.Using Group policy we can set the privileges to the shared folders.

141. What is folder sharing?

Folder sharing is a utility of modern OS, through this we can share the necessary files and documents over the network/within the network for accessing remotely.

142. What is difference between NAT and PAT?

NAT is Network address Translation (IP address translate from local IP to global IP and vice versa)PAT is Port address translation (port are translate from local to global IP's) like on port 8080 web service port 80 will work on PAT. It is more over NAT only.

143. Explain the layered aspect of a UNIX system. What are the layers? What does it mean to say they are layers?

A UNIX system has essentially three main layers:

# The hardware

# The operating system kernel

# The user-level programs

The kernel hides the system's hardware underneath an abstract, high-level programming interface. It is responsible for implementing many of the facilities that users and user-level programs take for granted.

The kernel assembles all of the following UNIX concepts from lower-level hardware features:

# Processes (time-sharing, protected address space)

# Signals and semaphores

# Virtual Memory (swapping, paging, and mapping)

# The file system (files, directories, namespace)

# Pipes and network connections (inter-process communication)

144. What is Semaphore? What is deadlock?

Semaphore is synchronization tool to solve critical-section problem, can be used to control access to the critical section for a process or thread. The main disadvantage (same of mutual-exclusion) is requiring busy waiting. It will create problems in a multiprogramming system, where a single CPU is shared among many processes.

Busy waiting wastes CPU cycles.

Deadlock is a situation when two or more processes are waiting indefinitely for an event that can be caused by only one of the waiting processes. The implementation of a semaphore with a waiting queue may result in this situation.

145. What is a router? What is a gateway?

Routers are machines that direct a packet through the maze of networks that stand between its source and destination. Normally a router is used for internal networks while a gateway acts a door for the packet to reach the 'outside' of the internal network.

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146. What is UTP?

UTP - unshielded twisted pair 10BASE-T is the preferred Ethernet medium of the 90s. It is based on a star topology. It provides a number of advantages over coaxial media.

It uses inexpensive, readily available copper phone wire. UTP wire is much easier to install and debug than coax. UTP uses RG-45 connectors, which are cheap and reliable.

147. How can you recover a file encrypted using EFS?

Use the domain recovery agent.

148. What is the difference between forward lookup and reverse lookup in DNS?

Forward lookup is name-to-address; the reverse lookup is address-to-name.

149. What is LMHOSTS file?

It is a file stored on a host machine, which is used to resolve NetBIOS to specific IP addresses.

150. Should we deploy IPSEC-based security or certificate-based security?

They are really two different technologies. IPSec secures the TCP/IP communication and protects the integrity of the packets. Certificate-based security ensures the validity of authenticated clients and servers.

151. How do cryptography-based keys ensure the validity of data transferred across the network?

Each IP packet is assigned a checksum, so if the checksums do not match on both receiving and transmitting ends, the data was modified or corrupted.

152. What is binding order?

The order by which the network protocols are used for client-server communications is binding order. The most frequently used protocols should be at the top.

153. What is data link layer in the OSI reference model responsible? Data link layer is located above the physical layer, but below the network layer.

Taking raw data bits and packaging them into frames. The network layer will be responsible for addressing the frames, while the physical layer is responsible for retrieving and sending raw data bits.

154. What are the networking protocol options for the Windows clients if for some reason you do not want to use TCP/IP?

NWLink (Novell), NetBEUI, AppleTalk (Apple).

155. What authentication options do Windows 2000 Servers have for remote clients?

Windows 2000 Servers have PAP, SPAP, CHAP, MS-CHAP and EAP.

156. How can you force the client to give up the DHCP lease if you have access to the client PC?

Ipconfig /release

157. We have installed a new Windows-based DHCP server, however, the users do not seem to be getting DHCP leases off it.

The server should authorize first with the Active Directory.

158. I cannot seem to access the Internet, do not have any access to the corporate network and on ip configuration my address is 169.254.*.*. What happened?

The 169.254.*.* netmask is assigned to Windows machines running 98/2000/XP if the DHCP server is not available. The name for the technology is APIPA (Automatic Private Internet Protocol Addressing).

159. Describe how the DHCP lease is obtained.

It is a four-step process consisting of (a) IP request, (b) IP offer, © IP selection, and (d) acknowledgement.

160. What is the difference between an abstract class and an interface?

An abstract class may have fields and some implemented methods. An interface has no implementation, only constants and method declarations.

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161. What is the goal of the shortest distance algorithm?

The goal is completely fill the distance array so that for each vertex v, the value of distance[v] is the weight of the shortest path from start to v.

162. What is the null pointer in C++?

The null pointer is a special C++ pointer value that can be any pointer does not point anywhere. It is the constant NULL form stlib.h

163. What is the time complexity of matrix multiplication?

void Mult_Matrix(matrix A, matrix B, matrix C){int i, j, k;for ( i = 1; i < N; i++)for ( j = 1; j < N; j++ ){C[i][j] = 0;for ( k = 0; k < N; k++ )C[i][j] = A[i][j]*B[k][j];}return;}

The time complexity of matrix multiplication is O (N^3)

164. What is TCP/IP?

Protocol - Set of rules and regulation, which are necessary for communication the data between one or more computers.

TCP/IP- In same manner Transmission control Protocol and Internet Protocol are the group of the protocol, which is supported by various operating system (windows, Linux, sun, Macintosh, Polaris etc.) for communicating data frequently without interruption.

These protocols are follows IEEE standards.

165. How do you configure DHCP server?

DHCP Is A Server Service. Before Installation of DHCP, We should install DNS Active Directory in Server Only Assigning IP Address to Clients.

166. Describe the OSI model.

Open System Interconnection is an ISO standard for worldwide communication that defines a networking framework for implementing protocols in seven layers. The seven layers are:

1) Application Layer

2) Presentation Layer

3) Session Layer

4) Transport Layer

5) Network Layer

6) Data Link Layer

7) Physical Layer

167. What is a DNS? How does it work?

DNS stands for Domain Name System. DNS is used to IP address to name resolution.

168. Define terminal services?

Terminal Services is a component of Microsoft Windows operating systems (both client and server versions) that allows a user to access applications or data stored on a remote computer over a network connection. Terminal Services is Microsoft's take on server centric computing, which allows individual users to access network resources easily.

169. Why do we use Subnet mask? What are its uses?

Subnet mask is use to isolate the network ID and Host ID. e.g. - if an IP is 192.168.0.1 then the default subnet is 255.255.255.0 because it is a C Class Address C Class Add. Have three network octate and one host octate i.e.

Network ID: 192.168.0.0

Host ID : 0.0.0.1

170. What is RAS Server?

Remote Access services (RAS) on Wide Area Network (WAN) Connection.

171. What is the difference between BRI and PRI Port?

BRI PORT -2B Chan1D Chan (Basic rate Interface)

1B----64kbps

1D ----16Kbps

PRI Port----24Bchan 1D Chan (primary rate Interface)

172. What is thhe difference between public IP and private IP?

Public IP are the IP that can be accessed by every onetime very user has the access to this IP's e.g. yahoo.com, google.com etc are the pubic IPs.

Private IP's are the IP that are accessed by every one, I.e. they are excessively owned by an organization, only the user of that organization has the access to this IP's.

Ranges of private IP address are

Class A 10.0.0.1 to 10.255.255.254

Class B 172.16.0.1 to 172.31.255.254

Class C 192.0.0.1 to 192.255.255.254

Excluding imps are public IP's.

173. What is difference between TCP/IP and UDP?

TCP - Transfer Control Protocol is:a. Reliableb. Connection oriented.c. Acknowledgement

UDP - User Datagram Protocol is none of the above.

174. Difference between subnet masks and default gateway?

Subnet mask is nothing but a playing of network and Default gateway is communicate to one network to another network given to router all pc in the network communicate to that particular default IP address.

175. What is Frame Relay?

Frame relay is a packet switching technology. It will operate in the data link layer.

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176. What is the difference between packet switched, cell switched and circuit switched technology?

Packet switch: here the packets send by the user takes different path each time it is send.

Circuit switch: here the packets are send through a virtual connection is this every packet from a sender at a particular time is send through that dedicated path only

Cell switch: in ATM jargon the packets are called are cells

177. What is difference between Domain and Work group?

Workgroup:

1. All computers are peers; no computer has control over another computer.
2. Each computer has a set of user accounts. To use any computer in the workgroup, you must have an account on that computer.
3. There are typically no more than ten to twenty computers.
4. All computers must be on the same local network or subnet.

Domain:

1. One or more computers are servers. Network administrators use servers to control the security and permissions for all computers on the domain. This makes it easy to make changes because the changes made to all computers.
2. If you have a user account on the domain, you can log on to any computer on the domain without needing an account on that computer.
3. There can be hundreds or thousands of computers.
4. The computers can be on different local networks.

178. Why do we need IP address when the MAC address is unique? Cant we communicate only with the MAC address?

MAC address is the basis on which communication occurs. However, we need IP address to be able to create a routing table, which enables faster communication. Many communication algorithms take use of IP addresses (Network address + Subnet masks) to be able to route packages faster.

179. What is the difference between networking and remote networking?

The main difference between networking and remote n/w, is the network which we use in offices or other places locally such LAN or INTRANET and remote n/wkg is one in which we use RAS or TERMINAL Services to communicate with the remote users such WAN or EXTRANET.

180. What is intra-VLAN how does it work. Where do we create a VLAN if we enable one trucking on each side of switch. What is supernating?

Virtual LANs (VLANs) divide one physical network into multiple broadcast domains. However, VLAN-enabled switches cannot by themselves, forward traffic across VLAN boundaries. Therefore, you need to have routing between these VLANs, which is inter- VLAN routing. You can achieve this by using either a Layer 3 switch or a router.Host Portion Borrowed From Network Portion is Called SUPERNATING

181. What is the full form of "ping" (network command)?

PING Stands for Packet Inter Net Gopher.

182. What is pulse code modulation?

(PCM) a way to convert sound or analog information to binary information (0s and 1s) by taking samples of the sound and record the resulting number as binary information. Used on all CDs, DVD-Audio, and just about every other digital audio format. You can see on DVD-Video.

183. Can we have two DHCP servers within one network? If not, why? If yes, will the IP address conflict?

No, we cannot have two DHCP servers in one network, coz it provide IP address to the clients. If two servers are supposed to distribute at a time there will be a conflict of the given and reserved IP addresses between two distribution points.

184. What is Protocol? How many types of Protocols are there?

Protocol usually refers to a set of rules that define an exact format for communication between systems. For example, the HTTP protocol defines the format for communication between web browsers and web servers, the IMAP protocol defines the format for communication between IMAP email servers and clients, and the SSL protocol defines a format for encrypted communications over the Internet.

185. Explain practical uses of Active Directory. What is printer server?

Active directory as per name it is the directory of active objects in you Domain. Active directory first time introduced in windows 2000 family, in active directory, we can maintain all user records, printer, computer, groups, and OU records. Through active directory we can easily maintained or controlled all the domain resources. Active directory installed when you configure your server as Domain server.Printer Server on which machine printer attached physically and shared for everyone and you can specify permission and priority settings as per environment. Through printer, we can keep records like printing copies per user on many things.

186. What is DHCP Server?

DHCP is used to assign IP address (which are defined in scope only) automatically to the system in the network. It makes life very much easier than previous WINS Server. In addition, it provides Static IPs to whatever server require like DNS FTP.

187. What is HPOV? How does it work? What are its monitoring tools?

HP Open View is a suite of business computer management or "e-services" programs from Hewlett-Packard, which states that the suite is "among the world's 20 largest software businesses". The Open View programs HP 9000 and e3000 business server customers. An HP customer's IT professionals can use Open View to manage applications, device availability, network conditions and status, system performance, service and program maintenance, and storage resources.

188. What is spanning tree? How does it work in VLAN?

Spanning tree protocols main takes is to stop network loops from occurring on your layer 2 networks. Network loops create broadcast storms and are responsible for additional overhead on the network.

189. What is the difference between TCP/IP and NETBEUI protocol?

The main difference is that NetBEUI is a non-routable protocol so there is no moving packet from one network to another; TCP/IP on the other hand is routable so you can connect multiple networks to share info and Frag! The internet is a bunch of TCP/IP networks connected together!

190. User(s) are complaining of delays when using the network. What would you do?

1. If you are using a hub, replacing that with switches will reduce the delay in case many users simultaneously access the network, copy files etc.2. Firewalls and antivirus software's cause network delay. If you have some AV of firewalls installed, uninstall it and check the speed. If you find improvement, u can install a better AV although that will cause delay to some extent.3. Virus / malwares cause network delay. Reinstall the OS, use some updated AV, and check it.4. If you mean delay in Internet connectivity then you have to go for greater bandwidth.

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191. What are the features of BGP Protocol? How it is different to other protocol

Border Gateway Protocol is the core routing protocol .It works by maintaining a table of IP networks, which designate network reach ability among autonomous systems (AS). It is described as a path vector protocol BGP does not use traditional IGP metrics, but makes routing decisions based on path, network policies, and/or rule sets. BGP replace the EGP routing protocol to allow fully decentralized routing in order to allow the removal of the NSFNet internet backbone network.

192. Explain distance vector routing algorithm with the help of suitable example.

Distance Vector Routing Algorithms calculate a best route to reach a destination based solely on distance. E.g., RIP. RIP calculates the reach ability based on hop count. It is different from link state algorithms, which consider some other factors like bandwidth and other metrics to reach a destination. Distance vector routing algos are not preferable for complex networks and take longer to converge.

193. A person would like to access a file on another computer (connected via LAN) while working with safe mode. What should he do?

Start the computer with "safe mode with networking". While starting the computer press F8 and four five option will come choose the above option then hope you will access that particular file through LAN.

194. What is the difference between L3 Switch and Router, if they perform the same function why do we need both of them?

Layer 3 switches do routing with ASIC chips. Routers do it with a microprocessor and its associated software. Therefore, the Layer 3 switches are much faster than traditional but cost more. We need them both because in many situations a slow router is sufficient and cheaper than a gigabit layer 3-switch router.

195. What is the difference between Client and desktop Operating systems?

Desktop operating system is a standalone operating system, able to perform all operations and requests independently. Client o/s cannot do that, moreover client uses all s/w via requests to servers. A node connected to server (Linux concept).

196. Why is OSI model layered?

It provides a structural approach to troubleshoot an issue.

197. What is difference between ISDN and ATM?

ISDN is an example of Circuit switching but ATM is Packet Switching or Cell switching.

198. What is the difference between unshielded twisted pair (UTP) and Shielded twisted pair (STP)?

The most commonly used form of twisted pair is unshielded twisted pair (UTP). It is just two insulated wires twisted together. Any data communication cables and normal telephone cables are this type. Shielded twisted pair (STP) differs from UTP in that it has a foil jacket that helps prevent crosstalk and noise from outside source. In data communications there is a cable type called FTP (foil-shielded pairs) which consists of four twisted pair inside one common shield (made of aluminum foil).

199. Why we use cross cable to connect same devices?

Same devices like PC-2-PC, it uses (NIC for PC) 1, 2 for transmission 3, 6 for reception. If we do not use cross cable then we cannot transfer data.While in the case of switch/hub they receive (NIC of SWITCH/HUB) data on 1, 2 transmit on 3, 6.That is why we use straight cable for de-similar host cross cable for similar hosts.

200. What is the bandwidth of a Switch and a Hub?

Hub bandwidth is 10 mbps; While Switch Bandwidth is 100 mbps.

201. What is RIP what is the use of RIP?

RIP (routing information protocol) is a distance vector dynamic routing protocol. It is used where there is less number of routers.Its max hop count is 15. It broadcast its entire routing information in every 30 seconds. It is a class full routing protocol.RIP version 2 is a classless routing protocol.

202. Is the client a server at a particular point of time? If yes then why what is it called?

No. client is not a server at a particular point of time. However, in some other time it may act as a server depending upon its configuration.

203. What is leased line modem? How it works in ISP?

Modem which works on isdn line, which is leased from some ISP, it is a point-to-point connection, very helpful for taking backup by the high end user as it is faster.

204. Can a single VLAN accommodate 254 computers?

Yes, only thing we need is a pc having ip add. In same subnet (e.g. 192.168.10.1 to192.168.10.254)

205. Why do we use bit stuffing and character stuffing?

The flag bits in the data link layer are of the form 01111110. If there is data that takes the same form, it will be misinterpreted as a flag bit. In order to avoid this we stuff additional bits at the sending end and de-stuff the same at the receiving end.

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206. Users are complaining of delay when using the network. How would you resolve it?

Mostly the physical layer is responsible for the delay in the network, so first check the connection and if still it does not work,call a network administrator from some reputed company.

207. Define networking.

In information technology, a network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain sub networks.

208. What is mean by Client?

Client is a system which houses the Client operating system like windows 95/98/me/2000professional/xp in the LAN and sharing the resources from the server.

209. What does u mean in networking?

It is an interconnected collection of autonomous computers, which can exchange information.

210. What is a device manager?

Device manager is a device which contains all information of input output devices.

211. How can we access the server socket in our client program in order to write data to server from client?

Using READ () FUNCTION. We can access the server socket when we want to write from client to the server.

212. What is metro

A Metro Ethernet is a computer network based on the Ethernet standard and which covers a metropolitan area.

213. What are the seven layers of OSI model.

OSI has 7 Layers

1. Physical Layer
2. Data link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Application Layer
7. Presentation Layer.

214. What is protocol?

It is a set of rules to communicate between computers. Alternatively, the language the computer speaks to communicate between none to node said to be protocol.

215. From which DHCP server is the client going to take IP, if 2 DHCP servers are present in Network?

There will not be two DHCP servers in one network.

216. Which features make Ethernet stand better than Internet?

The speed is first feature upon which Ethernet is better than Internet Others features are direct access to computers.

217. What is VLAN?

To reduce broadcast we use VLAN. By default switch has unique vlan1. There are two types of VLAN membership 1) static VLAN membership 2) dynamic VLAN membership.

218. What is multi casting?

Multicasting refers to a system, where a computers or network devices (node) sends out a message to a group of computers or network devices (node) in a network.

219. What is an IP address and what is the use of it?

IP address is a protocol, which can define to each pc. IP address is a path of network to flow.

220. How do we repair .pst file?

"Scanpst*.*" searches the file in your C: then run this program. Then you can repair your .pst files.

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221. What is mean by spare ware? What is the difference between spare ware and anti virus?

A spare ware is software that monitors the user's behavior and anti-virus is software that protects the system from viruses.

222. What is class-A, B, C, D IP address in detail?

1-126 127 it's a Loopback IP B: 128-191 c: 192-223 d: 223-247 Multicasting IP's

223. If you have 10 systems, what would you connect it with? Switch or hub?

To connect 10 systems we can use either switch or hub. As switch is better because, it does unicasting whereas, Hub does broadcasting. In addition, we have to select star, bus, ring topology.

224. What is networking?

Networking is the engineering discipline concerned with communication between computer systems or devices.

225. What is a proxy server?

A proxy server is a process that acts like a switchboard through a firewall to manage the various types of permitted communications with the outside world. Proxy servers may also use caching to make communications more efficient.

226. How many types of networks are there?

Types of network based on geographic are LAN, CAN, MAN, WAN Based on Server OS nature Centralized [domain] model or peer-to-peer [workgroup] model based on media like arcnet, Ethernet, token ring, wireless etc.

227. What are the the core naming mechanism, Domain Name System (DNS)?

A Domain Name system is used to convert the names of the website on the internet to IP addresses. The domain names for each IP addresses are stored in a database that is distributed across different servers. A domain name space consists of a tree of domain names. The tree has zones. Zones consist of a collection of connected nodes. These nodes are served by a name server. A domain name is usually in the form of mydomain.com. Here, .com is the top level domain. Where as mydomain is the sub domain or subdivision. A host name is a domain name that has one or more IP addresses associated with it.

228. Describe the basics of the internet routing.

When a source sends a packet to a destination, this packet has a specific path or route it follows. Different routing protocols are used to find the shortest path to the destination. The protocols maintain routing tables. Routing tables consist of a set of rules used to determine where these packets will travel. When a packet is received, a network device examines the packet and matches it to the routing table entry providing the best match for its destination. The packet keeps hopping until it reaches its destination.

229. Explain how names are translated (resolved) into IP address.

Domain Name server or DNS is used to resolve names into IP addresses. When a web address is entered into the browser, the DNS client sends a request to the DNS server to find the corresponding IP address for the name. The DNS server receives this request and searches for the corresponding IP address in the database. If at this point the resolution fails, this server sends this request to the parent server. The request keeps going up the hierarchy to the parent servers or the closest authoritative of the DNS server to resolve the address. If the request times out an error is retuned to the client. If the server is able to resolve the name requested, it passes the information back to the client. The next request sent by the client is to request for a web page for the IP address.

230. Explain the structure and use of internet addresses.

Each IP address is 32 bit long. In human language the IP addresses are written in dotted decimal notation. These are then converted to binary by the computer. Each IP address has two parts: Network identifier or a network ID and host ID. The current internet protocol standard is IPV4. The IP addresses are divided into three classes: a class A network, a class B network, and a class C network. Class A being the largest. The four digit numbers in an IPV4 address, each network of class A will have different first number, and then its network will be addressed by the rest of the three numbers, or three bytes. The IP addresses identify a machine to deliver packets and load web pages.

231. What is Routing Protocol?

Routing protocol is the way to send routing information between any routers in an autonomous system.

232. Explain Maximum Transfer Unit, MTU.

MTU specifies the largest amount of data that can be transferred across a network.

233. What is Address Resolution Protocol (ARP)?

Address Resolution Protocol ARP, is responsible for mapping an IP address to its corresponding physical network address. It is mostly seen on Ethernet network.

234. What is subneting?

Subnet adds one level to the way IP address is represented. It logically organizes the network. For instance, it can logically group computers belongs to the finance department.

235. Define IP multicast.

IP multicast technology reduces traffic by sending stream of information to many recipients at one go. Video conferencing, stock quotas are the examples based on IP multicast.

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236. What is Network Address Translation?

Network Address Translation acts as an agent between the Internet and a local network. It is a dynamic method which is used to minimize Internet connectivity needs. Network address translation describes the rewriting of the Internet Protocol (IP) addresses of data packets so that multiple transmissions require only one IP address.

237. What is the difference between public and private IP?

A public IP address allows equipment accessible to everyone on the internet. A private IP address is for private use within the network and allows many more PCs to be connected. If you are using a private IP and wants VOIP, you need to change to a public IP address.

238. Difference between Static and Dynamic IP.

Static IP is also called as permanent address assigned to each device in a network, whereas Dynamic IP, a temporary address assigned to the device via DHCP software. IP address assigned to your service by your cable or DSL Internet provider is typically dynamic IP. In routers and operating systems, the default configuration for clients is dynamic IP

239. How would you define IP address?

IP address or Internet Protocol address is the address of a device attached to an IP network (TCP/IP network). It is a must for every client, server and network device to have a unique IP address for each network connection (network interface). Every IP packet contains a source IP address and a destination IP address. As a device moves from one network to another, its IP address changes.

240. What is a stream socket?

A stream socket provides two way communications between a client and server. This communication is reliable and sequenced. Stream sockets are above TCP to run across any networks. They provide unduplicated flow of data and have well established mechanism for creating and destroying connections and for detecting errors.

241. Datagram vs. stream.

Stream can be considered as a pipe that allows full duplex connection. A datagram or a packet on the other hand, has a source and a destination. There is no connection. Stream is like a communication channel while datagram is completely self contained. Streams provide a reliable and sequenced communication. Datagram's on the other hand are unreliable and no sequence maintained.

242. What is the socket?

A socket is used to connect an application to a network protocol. A socket enables communication between a client and a server. The communication is started when the client is assigned a local port number, and binds a socket to it. The client writes on the socket and gets information from server by reading it.

243. Explain why use Multicasting.

* a. When the same message or packet needs to be sent to multiple destinations, multicasting is used.
* b. Within campus and offices, using multicasting file distribution can be done.
* c. System messages, news and videos can be sent at the same time.
* d. More commonly used for audio and video streaming.

244. Describe how to control the scope of multicast transmissions.

Controlling the scope of multicast transmission restricts the range of group members. TTL (Time To Live) is one of the mechanisms to limit the scope. If the TTL value is small, packets would only be multicast to smaller distance destinations. More the value of TTL, more would be the scope of transmission to a larger number of machines. Administrative scoping is another mechanism. In this, transmission is restricted to a specific address space of an organization or a site.

245. Describe how the multicast protocol works.

Multicast protocol or Internet protocol delivers a singles message to multiple machines. One packet from the source is replicated and sent to the destination. Every multicast message requires a multi case group. The group defines the addresses which will receive the message. The group is defined by the class D address. Different routing protocols are used to find the multicast groups and build routes for them. Distance Vector Multicast protocol is one of them. The receiver, to whom the multicast packet is sent to, needs to ‘join' the group. Joining the group is enabled and managed by IGMP. Multicast routers are used to transmit the messages from one network to another.

246. Define IP multicast.

IP multicast technology reduces traffic by sending stream of information to many recipients at one go. Video conferencing, stock quotas are the examples based on IP multicast.

247. What is multicasting?

Multicasting allows a single message to be sent to a group of recipients. Emailing, teleconferencing, are examples of multicasting. It uses the network infrastructure and standards to send messages.

248. Describe the format of RTP and RTCP packets.

The 32 bits of RTP packet format is as follows:- (L to R)

Bit 0-1:- Indicates version, currently 2
Bit 2:- P- indicates padding bytes
Bit 3:- X- Indicates presence of extension header
Bit 4-7:- CC- Contains number of CSRC identifiers that follows the header
Bit 8:- M- Current data has some special relevance (if set)
Bit 9-15:- PT- Indicates format of payload
Bit 16-31:- Sequence number
Timestamp: - 32bits - time stamp of packet
SSRC- Synchronization source identifier uniquely identifies the source of a stream.
CSRC -Contributing source IDs enumerate contributing sources to a stream which has been generated from multiple sources
Extension header: - first 32 bit word contains profile specific identifier and length specifier

The 32 bits of RTCP header format is as follows:- (L to R)
Bit 0-1:- Indicates version, currently 2
Bit 2:- P- indicates padding bytes
Bit 3 to 7:- Count of number of reception report blocks
Bit 8 to 15:- Type: - Determined RTCP packet type. Type can take values from 0 to 255
16 to 31:- Length- Length of RTCP packet - 1
SR: - Sender Report for transmission and reception from active senders
RR: - Receiver report for reception from in active senders
SDES: - Source description items
BYE- indicates end of participation
APP: - Application specific functions

249. Explain the use of RTP and RTCP protocols.

Use of RTP and RTCP:-

1. RTP can be used to transfer Real time data like voice packets.
2. RTP can be used with RTCP which makes it possible to monitor data.
3. Packet loss can be detected by RTP using Sequence number

RTCP provides Qos feedback :- Packets lost, round trip time

250. What is RTP Multiplexing?

RTP multiplexing allows multiple media flows within a single RTP data payload between two points. This means that it can be used to carry multiple streams of data in one RTP packet. RTP multiplexing will reduce the bandwidth used. RTP multiplexing will also increase scalability.

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251. What is RTP?

Real-Time Transfer Protocol lays a standard or a way to transfer or manage real time data over a network. It does not guarantee the delivery of data or provide any quality of service. However it helps to manage the data. Which means that RTP can be used deliver the necessary data to the application to make sure it can put the received packets in the correct order Real time data examples could be audio and video

252. Why do we need a subnet mask?

A subnet mask allows identification of host part and network part of an IP address. Subnet mask can be used to find if an IP address is present on a subnet or not.

253. Explain the importance of increasing and decreasing subnet bits.

Adding 1's as a bit means increasing the subnets and decreasing the hosts. Removing or decreasing 1's means decreasing subnets and increasing hosts. Hence by increasing or decreasing the subnet architecture can be decided as per needs.

254. What is custom Subneting?

Subnets that can be customized; i.e. modifying the dividing point between subnet ID and host ID to suit the needs of our network. The subnet mask that we use when creating a customized subnet is, called a custom subnet mask. This custom subnet mask is used to find the customization.

255. Explain the advantages of using Subneting.

Advantages of using Subneting:-

* Easier network management and trouble shooting
* Routing table's size is reduced which means faster network transfers
* Solves network congestion problems:- Since the complete network is divided into smaller networks
* Network addresses can be decentralized e.g. the administrator of the network can monitor the subnet

256. Describe the concept of Subneting.

Subneting is a process of breaking the network into smaller units. These units care called as subnets. Here a subnet could be several machines in a single LAN. Networks using IP can create sub networks of logical addresses. With every IP address there some of the bits in the machine can be used to identify a specific subnet. The IP address then contains three parts: the network number, the subnet number, and the machine number

257. Explain static and dynamic tunnels.

Tunnels that are created manually are static tunnels. Tunnels that are auto discovered are dynamic tunnels. In dynamic tunneling, tcp connections can be checked dynamically. If no connections exist that are routed through the tunnel, a check for more suitable gateway can be done. Static tunneling may at times require dedicated equipments.

258. What are voluntary and compulsory tunnels?

Voluntary Tunneling:
Users computer is an end point of the tunnel and acts as tunnel client. Here the client or user issues a request to configure and create a voluntary tunnel. They require a dial up or LAN connection. Example of dial up connection is internet at home where a call is made to the ISP and connection is obtained.

Compulsory tunneling:
In compulsory tunneling, instead of the user a vpn remote access server configures and creates a tunnel. Hence, the end point is the Remote sever not the user.

259. What is Tunneling?

Tunneling is a mechanism provided to transfer data securely between two networks. The data is split into smaller packets and passed through the tunnel. The data passing through the tunnel has 3 layers of encryption. The data is encapsulated. Tunneling can be approached by Point to Point tunneling protocol.

260. What are the different authentication methods used in VPNs?

The authentication method uses an authentication protocol. The methods are:

* EAP authentication method: Extensible authentication protocol authenticates remote access connection. The authentication mechanism is decided between the remote VPN client and authenticator (ISA). The mechanism is typical in which authenticator requests for authentication information and the responses are given by the remote VPN client.
* MS Chap Authentication method: Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) starts with the authenticator (Remote access server) challenge. The challenge to the remote access client sends a session identifier and challenge string. The client in response sends the nonreversible encryption of the string, the identifier and password. Authenticator checks the credentials and grants access on a successful authentication.
* Unencrypted passwords (PAP):- Uses plain text passwords. Does not involve encryption. Used for less secure clients.
* Shiva Password Authentication Protocol (SPAP):- It is a password authentication protocol. It is less secure as the same user password is always sent in the same reversibly encrypted form

261. What are the different types of VPN?

* Remote Access VPN:- Also called as Virtual Private dial-up network (VPDN) is mainly used in scenarios where remote access to a network becomes essential. Remote access VPN allows data to be accessed between a company's private network and remote users through a third party service provider; Enterprise service provider. E.g Sales team is usually present over the globe. Using Remote access VPN, the sales updates can be made.
* Site to Site VPN - Intranet based: This type of VPN can be used when multiple Remote locations are present and can be made to join to a single network. Machines present on these remote locations work as if they are working on a single network.
* Site to Site VPN - Extranet based: This type of VPN can be used when several different companies need to work in a shared environment. E.g. Distributors and service companies. This network is more manageable and reliable.

262. What is VPN (Virtual Private network)?

Virtual Private network is a network that used the public telecommunication infrastructure. This means that it used public wires to connect the nodes. E.g. Internet. VPN supports remote access to computers and allow data to be transmitted over this public network. Even though the data is transmitted over a public network, encryption and decrypting data to ensure security.

263. What is Trusted and Untrusted Networks?

Trusted networks:
Such Networks allow data to be transferred transparently. The machines using a trusted network are usually administered by an Administrator to ensure that private and secured data is not leaked. Access to this network is limited. Computers using trusted networks are more secured and confidential because of strong firewalls.

Untrusted networks:
Such networks are usually administered by the owners. They can allow improper access to sensitive or personal data. These machines are usually separate. Such machines could me more prone to attacks.

264. TCP vs. UDP.

TCP guarantees the delivery of data. UDP on the other hand, does not guarantee delivery of data. TCP delivers messages in the order they were sent. UDP has no ordering mechanisms. In TCP data is sent as a stream while UDP sends data as individual packets. UDP is faster than TCP. TCP is a connection oriented protocol while UDP is connectionless.

265. What is UDP protocol?

User Data Protocol is a communication protocol. It is normally used as an alternative for TCP/IP. However there are a number of differences between them. UDP does not divide data into packets. Also, UDP does not send data packets in sequence. Hence, the application program must ensure the sequencing. UDP uses port numbers to distinguish user requests. It also has a checksum capability to verify the data.

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266. What is TCP protocol?

Transmission control Protocol is used to establish communication between nodes or networks and exchange data packets. It guarantees delivery of data packets in the order they were sent. Hence it is most commonly used in all applications that require guaranteed delivery of data. It can handle both timeouts (if packets were delayed) and retransmission (if packets were lost). The stream of data is transmitted in segments. The segment header is 32 bit. it is a connectionless communication protocol at the third level (network) of the OSI model.

267. What is TCP windowing concept?

TCP windowing concept is primarily used to avoid congestion in the traffic. It controls the amount of unacknowledged data a sender can send before it gets an acknowledgment back from the receiver that it has received it.

268. Explain User Datagram Protocol, UDP.

The UDP is a connectionless, unreliable service. UDP messages can be lost and duplicated.

269. Explain Transmission Control Protocol, TCP.

TCP ensures reliable and end to end delivery of segments of information. Segments are acknowledged to the source when received by the destination. Data is broken up into segments and sequenced properly before transmission. This arrangement of segments allows destination to trace lost data in transmission.

270. What is the firewall?

A firewall is a hardware or software installed to provide security to the private networks connected to the internet. They can be implemented in both hardware and software, or a combination of both. All data entering or leaving the Intranet passes through the firewall which allows only the data meeting the administrators' rules to pass through it.

271. What is the Digital Signatures?

Digital signature is an attachment to an electronic message used for security purpose. It is used to verify the authenticity of the sender.

272. What is the Public Key Encryption?

Public key encryption use public and private key for encryption and decryption. In this mechanism, public key is used to encrypt messages and only the corresponding private key can be used to decrypt them. To encrypt a message, a sender has to know recipient's public key.

273. What is Data encryption?

Data encryption ensures data safety and very important for confidential or critical data. It protect data from being read, altered or forged while transmission.

274. Describe the basics of internet routing.

When a source sends a packet to a destination, this packet has a specific path or route it follows. Different routing protocols are used to find the shortest path to the destination. The protocols maintain routing tables. Routing tables consist of a set of rules used to determine where these packets will travel. When a packet is received, a network device examines the packet and matches it to the routing table entry providing the best match for its destination. The packet keeps hopping until it reaches its destination.

275. What is Distance Vector Routing Protocols?

The main goal of Distance Vector Routing Protocols Is to find out the best path for he data packet to reach the destination. Distance here could be the hops. The three different types of Distance Vector routing protocols include:- Routing Information Protocol (RIP v1 and v2) and Interior Gateway Routing Protocol. The protocol is easy to manage however not well scalable.

The Distance Vector protocol initially prepares a Routing table which is shared with other routers. This routing table is shared between routers present in the same network. A new routing table is prepared when some new information is received from some other router. Now, the bad routing paths are removed keeping only the smallest hop paths. This new table is then communicated to other routers.

276. What is Routing Protocols?

Routing protocols are used to assist in achieving the basic purpose of routing. They specify the routers the method to communicate with each other. They help the routers select the best possible path between nodes. There are different types of protocols such as link-state routing protocols, path vector protocols and distance vector routing protocols. These protocols prevent routing loops to form or break if formed already. They help to decide preferred routes from a sequence of hop costs.

277. What is Routing table?

A routing table stores the routes of the various nodes in a network. Nodes can be any electronic device connected to the network. The table is usually stored in a router or the network computer as a database or file. This information helps to fond the best possible path. The routing table has at least 3 fields: the destination network id, cost of the path, next hop or address to send the packet.

278. What are the basic components of routers?

Components of Router

Internal components:

* ROM:- Used to store the routers bootstrap details, operating system software.
* Flash memory: - holds the operating systems images. The content is retained when the router is restarted.
* RAM: - Used to store the Routing tables, configuration files, caching and buffering details. Content is lost when lost router is switched off or restarted.
* NVRAM:- Stores the routers startup config files. Data is non volatile.
* Network interfaces to connect router to network.

External components:

* Virtual terminals: For accessing routers
* Network management stations

279. What is SNMP (Simple Network Management Protocol)?

SNMP or Simple Network Management Protocol is typically used for managing the network. Managing the network includes managing the nodes present in the network. These nodes may be server, routers, bridges and hubs. SNMP agents are used to achieve this. Managing the network is essential because it helps to monitor network performance, detect network faults or failures, audit network usage etc. the SNMP messages like TRAP, GET or SET may be invoked by network elements or network management system.

280. What is POP3 (Post Office Protocol 3)?

POP3 or Post Office Box 3 is used fro receiving emails. It is a client server protocol which holds the email. Once the email is downloaded from the server, POP3 deletes it from the server. Ordinal numbers are used to identify specific messages.

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281. What is SMTP (Simple Mail Transfer Protocol)?

SMTP or Simple Mail Transfer Protocol is used to send email messages between servers. The messages are retrieved using email clients. SMTP is more commonly used to send messages from a mail client to a mail server. And hence the email client like POP needs to be configured. Hence, SMTP is used to send emails while POP or IMAP are used to receive messages. It is usually operated on port25 on the internet.

282. What is NNTP (Network News Transfer Protocol)?

NNTP or Network News Transfer Protocol is used to manage the notes posted on Unset newsgroup (a collection of posted notes on a subject posted by different users). NNTP servers are responsible for managing Usenet newsgroup collected globally. A NTTP client is a part of the web browser also called as a news reader. It uses a reserver port no 119.

283. What is HTTP (Hypertext Transfer Protocol)?

HTTP or Hyper Text Transfer Protocol is provides a set of rules to transfer files, videos, images over the world wide web. When the web browser is opened, a HTTP request call is made. A web server contains a HTTP daemon. This daemon is used to wait for HTTP requests and handle them when they arrive. The web browser from where HTTP requests are made is called as a client. These requests are sent to the server. It uses a reserved port no 80.

284. What is FTP (File Transfer Protocol)?

FTP is File Transfer Protocol. It used to exchange files on the internet. To enable the data transfer FTP uses TCP/IP, FTP is most commonly used to upload and download files from the internet. FTP can be invoked from the command prompt or some graphical user interface. FTP also allows to update (delete, rename, move, and copy) files at a server. It uses a reserved port no 21.

285. What is TCP / IP protocol?

Transmission Control Protocol / Internet Protocol: - It is a family of protocols used for communication and connection between hosts on the internet. It is the most widely used standard for transmitting data over the internet. The four layers in the protocol are (from bottom to top):- Physical layer, Data link layer, Network layer, transport layer and application layer, also called as the OSI model. In TCP/IP , IP is responsible for forwarding packets while TCP ensures the correct delivery of data from client to server. TCP detects loss of data as well.

286. Explain PPP protocol.

Point to Point protocol helps communication between 2 computers over a serial cable, phone line or other fiber optic lines. E.g. Connection between an Internet Service Provider and a host. PPP also provides authentication. PPP operates by sending Request packets and waiting for Acknowledge packets that accept, reject or try to change the request.

The protocol is also used to negotiate on network address or compression options between the nodes. PPP has a number of phases as below:

* Link dead: - takes place when the connection fails.
* Link Establishment Phase: - Used to establish connection. If authentication is desired, it moves to next phase.
* Authentication Phase: - Allows the nodes to authenticate each other.
* Network-Layer Protocol Phase: - here, the network control protocols come into play. Data transport, closing of the protocols takes place in this phase.
* Link Termination Phase: - here, the connection is terminated.

287. What is IGMP protocol?

Internet Group Management Protocol, allows internet hosts to multicast. i.e. to send messages to a group of computers. There may be a group of internet hosts interested to multicast. IGMP allows router to determine which host groups have members on a given network segment. It helps to establish group memberships. It is commonly used for streamlining videos and gaming. The protocol can be implemented both as a host side and router side. The host side is responsible to notify its membership in a group. The notification is made to a local router. This local router (router side) in turn sends out queries.

288. What is NetBIOS protocol?

NetBIOS (Network Basic Input/Output System) Protocol allows applications on separate computers to communicate over a LAN. It runs over TCP/IP giving each computer in the network a NetBIOS name and IP address. E.g. It can be used for computers running Windows 2000 (or before) to join a computer network running Windows 2000 (or later).

289. What is CSMA and CD concept?

In CSDA (carrier sense multiple access), presence of any digital signal in a network is checked before transmission. Data transmission occurs only when no signal is sensed.

CD, Collision detection is responsible for monitoring carrier in order to avoid signal jam.

290. Explain token ring technology.

In this technology, all the devices are arranged in a circle. A token moves around the circular network. A device waits for the token before it sends its frame. Once it receives token, it initiates transmission of its frame.

291. Explain the use of network interface card, NIC.

NIC is used to connect computer to an Ethernet network.

292. What is Ethernet technology?

Ethernet technology is a high speed broadcast bus technology. In this type, all the station shares a single ether channel and receives every single transmitted signal.

293. What is Digital Signatures?

Digital signature is an attachment to an electronic message used for security purpose. It is used to verify the authenticity of the sender.

294. What is the Public Key Encryption?

Public key encryption use public and private key for encryption and decryption. In this mechanism, public key is used to encrypt messages and only the corresponding private key can be used to decrypt them. To encrypt a message, a sender has to know recipient's public key.

295. What is Data encryption?

Data encryption ensures data safety and very important for confidential or critical data. It protect data from being read, altered or forged while transmission.

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296. What are the types of firewalls?

Packet Filtering Firewall:
This type of Firewall detects packets and block unnecessary packets and makes network traffic release.

Screening Router Firewalls:
It's a software base firewall available in Router provides only light filtering.

Computer-based Firewall:
It's a firewall stored in server with an existing Operating System like Windows and UNIX.

Hardware base Firewall:
Its device like box allows strong security from public network. Mostly used by big networks.

Proxy Server:
Proxy server allows all clients to access Internet with different access limits. Proxy server has its own firewall which filters the all packet from web server.

297. What is firewall?

A firewall is a hardware or software installed to provide security to the private networks connected to the internet. They can be implemented in both hardware and software, or a combination of both. All data entering or leaving the Intranet passes through the firewall which allows only the data meeting the administrators' rules to pass through it.

298. Define gateway.

A gateway is a network point that provides entrance into another network. On the Internet, a node or stopping point can be either a gateway node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes. The computers that control traffic within your company's network or at your local Internet service provider (ISP) are gateway nodes.

299. What is a Router?

A router is a device or sometimes a software in a computer which decides the next network point to which a packet should be forwarded to reach its destination on Internet. It is usually included as part of the network switch and is located at a gateway, including each point-of-presence on the Internet. The router is connected to at least two networks and determines which way to send each information packet based on its understanding of the state of the networks it is connected to.

300. Bridge vs switch.

A bridge connects two different LAN networks. A switch is something like you can connect many computers to a switch and then one computer can connect to another through the switch. Switch is a unicast one to one connection

301. Define broadcast domain.

It is a logical area in a computer network where any computer connected to the network can directly transmit to any other computer in the domain without having to go through a routing device.

302. What is VPN?

A VPN is a service that offers secure, reliable connectivity over a shared public network infrastructure such as the Internet. VPNs maintain the same security and management policies as a private network. They are the most cost effective method of establishing a virtual point-to-point connection between remote users and an enterprise customer's network.

303. Define Spanning-Tree Protocol (STP)

Spanning-Tree Protocol (STP) as defined in the IEEE 802.1D is a link management protocol that provides path redundancy while preventing undesirable loops in the network. For an Ethernet network to function properly, only one active path can exist between two stations. Loops occur in networks for a variety of reasons. The most common reason you find loops in networks is the result of a deliberate attempt to provide redundancy - in case one link or switch fails, another link or switch can take over.

304. MAC vs. IP Addressing

Whereas MAC addressing works at the data link layer, IP addressing functions at the network layer (layer 3). It's a slight oversimplification, but one can think of IP addressing as supporting the software implementation and MAC addresses as supporting the hardware implementation of the network stack. The MAC address generally remains fixed and follows the network device, but the IP address changes as the network device moves from one network to another.

305. What Is a MAC Address?

MAC (Media Access Control) addresses are globally unique addressed that are written into hardware at the time of manufacture. The MAC address is a unique value associated with a network adapter. MAC addresses are also known as hardware addresses or physical addresses. They uniquely identify an adapter on a LAN. MAC addresses are 12-digit hexadecimal numbers (48 bits in length).

306. Define SMTP

SMTP - Short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers.

307. Define Telnet

Telnet is the main Internet protocol for creating a connection to a remote server.

308. Define DNS

The DNS translates Internet domain and host names to IP addresses. DNS automatically converts the names we type in our Web browser address bar to the IP addresses of Web servers hosting those sites. DNS implements a distributed database to store this name and address information for all public hosts on the Internet.

309. Describe Application layer.

The application layer is located at the top of the TCP/IP protocol layers. This one contains the network applications which make it possible to communicate using the lower layers. The software in this layer therefore communicates using one of the two protocols of the layer below (the transport layer), i.e. TCP or UDP. In computer networking, an application layer firewall is a firewall operating at the application layer of a protocol stack. Generally it is a host using various forms of proxy servers to proxy traffic instead of routing it. As it works on the application layer, it may inspect the contents of the traffic, blocking what the firewall administrator views as inappropriate content, such as certain websites, viruses, and attempts to exploit known logical flaws in client software, and so forth. An application layer firewall does not route traffic on the network layer. All traffic stops at the firewall which may initiate its own connections if the traffic satisfies the rules.

310. Explain the core naming mechanism, Domain Name System (DNS).

A Domain Name system is used to convert the names of the website on the internet to IP addresses. The domain names for each IP addresses are stored in a database that is distributed across different servers. A domain name space consists of a tree of domain names. The tree has zones. Zones consist of a collection of connected nodes. These nodes are served by a name server. A domain name is usually in the form of mydomain.com. Here, .com is the top level domain. Where as mydomain is the sub domain or subdivision. A host name is a domain name that has one or more IP addresses associated with it.

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311. Explain the functionality of PING.

Ping Is particularly used to check if the system is in network or not. It also gives packet lost information. In windows ping command is written as ping ip_address. The output returns the data packets information. The number of packets sent, received and lost is returned by PING.

312. What is multicasting?

Multicasting allows a single message to be sent to a group of recipients. Emailing, teleconferencing, are examples of multicasting. It uses the network infrastructure and standards to send messages.

313. Explain the different classes of addresses supported by IP addressing.

Computers using the TCP/IP for communication are uniquely identified by a 32 bit address called as an IP address. The routers use the IP address information to forward the packet to the destination computer.

IP addresses are categorized as:

Private address: these IP addresses are used exclusively within a private network and not for public to see.

Public Address: these are registered IP addresses used for public.

Each IP address has a network address and a host address. IP addresses are expressed in four sets of three numbers, separated with dots. Each set is called as an octet because when converted to binary; it denotes eight binary

314. Explain IP, TCP and UDP.

TCP - Transmission control Protocol is used to establish communication between nodes or networks and exchange data packets. It guarantees delivery of data packets in the order they were sent. Hence it is most commonly used in all applications that require guaranteed delivery of data. It can handle both timeouts (if packets were delayed) and retransmission (if packets were lost). The stream of data is transmitted in segments. The segment header is 32 bit. it is a connectionless communication protocol at the third level (network) of the OSI model.

IP - Internet protocol is used for transmission of data over the internet. IP uses IP addresses to identity each machine uniquely. Message is sent using small packets. The packet contains both the sender and receivers address. IP does not guarantee the delivery in the same order as sent. This is because the packets are sent via different routes. It is a connectionless communication protocol at the third level (network) of the OSI model.

UDP - User Data Protocol is a communication protocol. It is normally used as an alternative for TCP/IP. However there are a number of differences between them. UDP does not divide data into packets. Also, UDP does not send data packets in sequence. Hence, the application program must ensure the sequencing. UDP uses port numbers to distinguish user requests. It also has a checksum capability to verify the data.

315. What are network topologies? Explain Ring, Bus and Star topology.

A network topology describes the layout of a network. It describes how different nodes and elements are connected to each other. Different types of topology:

a. Ring:-

* All nodes connected with another in a loop.
* Each device is connected to one or more another device on either side.

b. Bus

* All nodes connected to a central and a common cable called as a back bone.
* In bus topology, the server is at one end and the clients are connected at different positions across the network.
* Easy to manage and install.
* If the backbone fails, the entire communication fails.

c. Star

* All nodes connected to a central hub.
* The communication between the nodes is through the hub.
* Relative requires more cables as compared to BUS. However if any node fails, it wont affect the entire LAN.

316. What is a network? What are the different kinds of network? Explain them.

A network is a group of computers or nodes connected together. They are connected with each other by communication paths.

Types of Networks:

LAN - Local Area Network connects a group of nodes covering a small physical area. LAN's are most commonly seen in offices, building etc. LAN's enable higher transfer rate of data, smaller coverage of area and hence less wiring.

WAN - Wide Area Network connects a group of nodes covering a wide area. WAN typically connects and allow communication between regions or national boundaries. The most common example of WAN is internet.

VPN - Virtual Private Network connects or links nodes in some larger area by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. It is used for secure communication through the public internet. VPN alone may not support explicit security features, such as authentication or content encryption.

Intranet - It is a set of networks under the control of a single administrative person. It can be considered as an internal network of an organization. If it is large, web servers are used to provide information to the users.

Extranet - It is a network that restricts itself within a single organization. It can be categorized as WAN, MAN etc. however; it cannot have a single LAN. It must have a connection (at least one) with external network.

317. Explain the 7 Layers of OSI.

Layer 1: Physical layer
It represents all the electrical and physical specifications for devices.

Layer 2: Data link layer
It provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical layer.

Layer 3: Network layer
The Network layer provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks.

Layer 4: Transport layer
It provides transparent transfer of data between end users.

Layer 5: Session layer
It controls the sessions between computers. It connects, manages and terminates the connections between the local and remote application.

Layer 6: Presentation layer
It transforms data to provide a standard interface for the Application layer.

Layer 7: Application layer
It provides a means for the user to access information on the network through an application.

318. Define File Transfer Protocol.

File Transfer Protocol (FTP), a standard Internet protocol, is the simplest way to exchange files between computers on the Internet. Like the Hypertext Transfer Protocol (HTTP), which transfers displayable Web pages and related files, and the Simple Mail Transfer Protocol (SMTP), which transfers e-mail, FTP is an application protocol that uses the Internet's TCP/IP protocols. FTP is commonly used to transfer Web page files from their creator to the computer that acts as their server for everyone on the Internet. It's also commonly used to download programs and other files to your computer from other servers.

319. Define the term Protocol.

Protocol is a standard way of communicating across a network. A protocol is the "language" of the network. It is a method by which two dissimilar systems can communicate. TCP is a protocol which runs over a network.

320. What is the difference Between an Intranet and the Internet?

There's one major distinction between an intranet and the Internet: The Internet is an open, public space, while an intranet is designed to be a private space. An intranet may be accessible from the Internet, but as a rule it's protected by a password and accessible only to employees or other authorized users.

From within a company, an intranet server may respond much more quickly than a typical Web site. This is because the public Internet is at the mercy of traffic spikes, server breakdowns and other problems that may slow the network. Within a company, however, users have much more bandwidth and network hardware may be more reliable. This makes it easier to serve high-bandwidth content, such as audio and video, over an intranet.

321. What is LAN?

LAN is a computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN). Most LANs connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.

322. What is "Gateway Of Last Resort"?

A Gateway of Last Resort or Default gateway is a route used by the router when no other known route exists to transmit the IP packet. Known routes are present in the routing table. Hence, any route not known by the routing table is forwarded to the default route. Each router which receives this packet will treat the packet the same way, if the route is known, packet will be forwarded to the known route.

323. Explain Circuit Level Gateway.

A circuit level gateway is used to find if a session in TCP handshaking is legitimate or not. It can be considered as a layer between application layer and transport layer. They protect the information of the private network they protect. Circuit level gateways do not filter packets.

324. What is an application gateway?

An application gateway is an application program that runs on a firewall between two networks. An application gateway is used for establishing connection between client program and destination service. The client negotiates with the gateway to communicate with the service of destination. Here, gateway can be called as a proxy. Hence, two connections are made. One between client and proxy; other, between proxy and destination service. Connections take place behind the firewall

325. Explain IP datagram, Fragmentation and MTU.

IP datagram can be used to describe a portion of IP data. Each IP datagram has set of fields arranged in an order. The order is specific which helps to decode and read the stream easily. IP datagram has fields like Version, header length, Type of service, Total length, checksum, flag, protocol, Time to live, Identification, source and destination ip address, padding, options and payload.

MTU:- Maximum Transmission Unit is the size of the largest packet that a communication protocol can pass. The size can be fixed by some standard or decided at the time of connection

Fragmentation is a process of breaking the IP packets into smaller pieces. Fragmentation is needed when the datagram is larger than the MTU. Each fragment becomes a datagram in itself and transmitted independently from source. When received by destination they are reassembled.

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326. What is IP Spoofing and how can it be prevented?

IP spoofing is a mechanism used by attackers to gain unauthorized access to a system. Here, the intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host. This is done by forging the header so it contains a different address and make it appear that the packet was sent by a different machine.

Prevention:-
Packet filtering: - to allow packets with recognized formats to enter the network
Using special routers and firewalls.
Encrypting the session

327. What is PPP protocol? Explain PPP packet format.

Point to Point protocol helps communication between 2 computers over a serial cable, phone line or other fiber optic lines. E.g. Connection between an Internet Service Provider and a host. PPP also provides authentication. PPP operates by sending Request packets and waiting for Acknowledge packets that accept, reject or try to change the request. The protocol is also used to negotiate on network address or compression options between the nodes.

Packet format:-

Flag field: 1 byte: - Indicates frames beginning or end
Address field: 1 byte: - Used for broadcast address (destination address)
Control field: 1 byte: - Used as a control byte
Protocol field: - 1 or 2 bytes: - Setting of protocol in information field (of datagram)
Information: - 0 or more bytes: - Datagram (whether it contains data or control information)
Padding: - 0 or more bytes: - optional padding
FCS: - 2 or more bytes: - error check sum

328. Explain how NAT works.

Network Address Translation translates and IP address used in a network to another IP address known within another network. A NAT table is maintained for global to local and local to mapping of IP's. NAT can be statically defined or dynamically translate from a pool of addresses. The NAT router is responsible for translating traffic coming and leaving the network. NAT prevents malicious activity initiated by outside hosts from reaching local hosts by being dependent on a machine on the local network to initiate any connection to hosts on the other side of the router.

329. What are the differences between a domain and a workgroup?

In a domain, one or more computer can be a server to manage the network. On the other hand in a workgroup all computers are peers having no control on each other. In a domain, user doesn't need an account to logon on a specific computer if an account is available on the domain. In a work group user needs to have an account for every computer.
In a domain, Computers can be on different local networks. In a work group all computers needs to be a part of the same local network.

330. Explain the concept of DHCP.

Dynamic Host Configuration Protocol is used assigning IP addresses to computers in a network. The IP addresses are assigned dynamically. Certainly, using DHCP, the computer will have a different IP address every time it is connected to the network. In some cases the IP address may change even when the computer is in network. This means that DHCP leases out the IP address to the computer for sometime. Clear advantage of DHCP is that the software can be used to manage IP address rather than the administrator.

331. Explain RSVP. How does it work?

Resource Reservation protocol is used to reserve resources across a network. It is used for requesting a specific Quality of Service (QoS) from the network. This is done by carrying the request (that needs a reservation of the resource) of the host throughout the network. It visits each node in the network. RSVP used two local modules for reservation of resources. Admission control module confirms if there are sufficient available resources while policy module checks for the permission of making a reservation. RSVP offers scalability. On a successful completion of both checks RSVP uses the packet classifier and packet scheduler for the desired Qos requested.

332. What are Ping and Tracert?

Ping and tracert are the commands used to send information to some remote computers to receive some information. Information is sent and received by packets. Ping I particularly used to check if the system is in network or not. It also gives packet lost information. In windows ping command is written as ping ip_address Tracert is called as trace route. It is used to track or trace the path the packet takes from the computer where the command is given until the destination. In windows ping command is written as tracert ip_address

333. What is the use of IGMP protocol?

Internet Group Management Protocol: - It allows internet hosts to participate in multicasting. The IGMP messages are used to learn which hosts is part of which multicast groups. The mechanism also allow a host to inform its local router, that it wants to receive messages.