1. Explain What is the difference between flow control and error control?

* Flow control: adjust and confirm data flow rate for successful transmission.
* Error Control: a way to recover corrupted data .

2. What is the port number of Telnet and DNS?

Telnet = 23 and DNS = 53

using telnet we can take command mode in the system , it work's under port no 23

3. What is sockets?

A socket is an abstraction that represents an endpoint of communication. Most applications that consciously use TCP and UDP do so by creating a socket of the appropriate type and then performing a series of operations on that socket. The operations that can be performed on a socket include control operations (such as associating a port number with the socket, initiating or accepting a connection on the socket, or destroying the socket) data transfer operations (such as writing data through the socket to some other application, or reading data from some other application through the socket) and status operations (such as finding the IP address associated with the socket).

4. Explain How does TCP try to avoid network meltdown?

TCP includes several mechanisms that attempt to sustain good data
transfer rates while avoiding placing excessive load on the
network. TCP's "Slow Start", "Congestion Avoidance", "Fast
Retransmit" and "Fast Recovery" algorithms are summarised in RFC
2001. TCP also mandates an algorithm that avoids "Silly Window
Syndrome" (SWS), an undesirable condition that results in very
small chunks of data being transferred between sender and
receiver. SWS Avoidance is discussed in RFC 813. The "Nagle
Algorithm", which prevents the sending side of TCP from flooding
the network with a train of small frames, is described in RFC

6. Explain How does ARP response the request?

ARP sent the request in broadcast, response is unicast

When a source sends arp request the switch broadcast the arp req. if it doesn't hav d destination mac address in its mac address table, if the destination mac is known then switch simply forwards the request to that particular host and the host sends the arp response to the switch and the switch will further send the arp response to the source requesting the mac address.

8. Explain How can we measure the performance of an IP link?

You can get a quick approximation by timing how long it takes to
FTP or RCP a large file over the link, but bear in mind that that
measurement will be skewed by the time spent in dealing with the
local and remote filesystems, not simply with the network itself.
And remember to measure the time it takes to receive a file, not
the time it takes to send it; the sender can report completion
even though large amounts of data are still buffered locally by
TCP and have not yet been delivered to the destination.

9. Explain Which layer is closer to the user?

There is only an application layer which is closer to user and also provides many application which user directly connected .for example web browser

10. Explain What is the Role of TCP/IP in data transmission from source to destination?

TCP/IP is a protocol stack used for data transmission from source to destination.
In the physical layer all the physical connections like LAN cards, cables etc will b there which will send data in the form of bits. layer 2 operates with frames where the switches comes into picture.
in the network layer which operates on packets.routing takes places, routers are the devices used for this.
transport layer is above the network layer and it uses mainly TCP/ UDP for transport of data.
the application layers is on top of this layer.

application layer
transport layer[tcp/udp]
network layer[routers]
datalink layer[switches]
physical layer[Network Interface card, cables etc]

for any transfer of data between 2 systems this TCP/IP stack comes into picture, whether it is file transfer or uploading something,sending an email etc. any application based on web will use TCP/IP

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