Friday 14 September 2012

CN Interview Questions-2


1. What is Mail Gateway
It is a system that performs a protocol translation between different electronic mail delivery protocols.

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

3. What are Digrams and Trigrams
The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.

4. What is silly window syndrome
It is a problem that 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.

5. What is 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.

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

7. What is 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.

8. 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.

9. What is 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.

10. What is 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. 

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