1. How frequency hopping is used for security in Bluetooth?

Blue tooth technology uses Adaptive Frequency Hopping and capable to reduce interference between wireless technologies with the help of 2.4 GHz spectrum. In order to take the advantage of the available frequency, Blue tooth's AFH works within the spectrum and is performed by the technology detecting other devices in the spectrum and avoiding the used frequencies. Efficient transmission within the spectrum at high degree of interference immunity is achieved by adapting hopping among 79 frequencies at 1 MHz intervals.

2. Why is Bluetooth 2.0 better than previous versions?

Bluetooth 2.0 is better than its predecessors because:

1. Bluetooth 2.0 is 3 times faster than 1.2
2. An additional modulation scheme is used
3. It is backwards compatible
4. The number of connections running concurrently are more
5. It is capable of recovering from errors and
6. Power consumption is less

3. What do you mean by the term Frequency-Hopping Spread Spectrum (FHSS)?

Flexibility and mobility are the growing reasons to use wireless LAN which uses radio frequencies for transmitting data. Wireless LANs are established for communicating with one another while on the go.

The data transmitting on one frequency for a specific time limit and jumping randomly to another and transmitting again is the process in FHSS. The RF circuits can utilize class C amplification, efficient non-linear with a normal 1 MHz bandwidth.

FHSS systems are better for use within indoors and in severe multipath environments. This is because of the frequency hopping scheme could defeat the multipath by hopping to a new frequency.

4. Explain the term Airport in Bluetooth?

Airport is standard (802.11) and has a faster transfer rate. Technologically it is more advanced, more rugged and smaller and capable of being used anywhere. It is 10mb/sec, 50 meters, 10 active devices. Apparently, Bluetooth is 1mb/sec, 10 meters and 7 active devices.

5. What method is used for Voice transfer? Brief about the method used?

For Voice transfer, SCO (Synchronous Connection Oriented) links are used for good synchronization and reliability.

6. Explain the following terms:
ICMP, ARP, Multicast, Broadcast?

Internet Control Message Protocol: This protocol is used for while checking the connectivity using ping command

Address Resolution Protocol: This protocol is used to know about the properties of TCP/IP. For example, to know other system MAC addresses.

Multicast: Communication between single sender and a list of select recipients in a network.

Broadcast: To send messages to all the recipients simultaneously in a network.

7. What is TCP connection establishment and tear down?

The following is the process for Tcp connection:

1. As connection is made by synchronizing sender and receiver and the OS is informed about the connection establishment.

2. Sender starts sending information and gets acknowledged. Soon after the sender sends the data, a timer is started.

3. When the sender is not received any acknowledgement ever after exceeding the timer's limit, the data is transmitted.

4. If windowing occurs, buffer on the receiver is full, then a stop signal is sent by the sender and stops sending information

5. Soon after processing all data, a go signal is sent by the sender, followed by transmitting data again.

8. What is Compulsory Tunnel?

The tunnel creation in compulsory tunnel, no action from the user and without allowing the user any choice is performed. Internet service provider access concentrator receives a point-to-point protocol packets from the user. The encapsulation of packets in L2TP and sending them through a tunnel to the L2TP network server is performed by the ISP. It is mandatory that the ISP is L2TP-capable.

9. What is Voluntary Tunnel?

The user creates a voluntary tunnel model. This model is typically uses a L2TP enabled client. An L2TP packet is sent by user to the Internet Service Provider which will in turn forward them on to LNS. The support of L2TP support is not needed by ISP. The L2TP tunnel initiator resides on the same system effectively playing as a remote client.

10. What is Point-To-Point Tunneling Protocol, PPTP?

PPTP is one of the methods to implement Virtual Private Networks. Confidentiality or encryption does not provided by PPTP. The reliability of PPTP is being tunneled for the purpose of providing privacy. PPTP works by sending Point-to-Point Protocol to the peer with the Generic Encapsulation protocol. Because of its easy way of configuration, it is most popular protocol used in VPNs. It was the first protocol for VPNs and was supported by Dial-up network of Microsoft.

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