Computer Network-III

1. 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.

2. 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.

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

4. What is region?
When hierarchical routing is used, the routers are divided into what we will 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.

5. 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.

6. 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.

7. Expand IDEA.
IDEA stands for International Data Encryption Algorithm.

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

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

10. What is IGP (Interior Gateway Protocol)?
It is any routing protocol used within an autonomous system.

11. What is EGP (Exterior Gateway Protocol)?
It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

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

13. What is BGP (Border Gateway Protocol)?
It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).

14. What is Gateway-to-Gateway protocol?
It is a protocol formerly used to exchange routing information between Internet core routers.

15. 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.

16. What is 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.

17. 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.

18. What is 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.

19. What is 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.

20. What is SLIP (Serial Line Interface Protocol)?
It is a very simple protocol used for transmission of IP datagrams across a serial line.

21. What is RIP (Routing Information Protocol)?
It is a simple protocol used to exchange information between the routers.

22. What is source route?
It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

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