Which of the following protocols is used for exchanging routing information between two gateways
in a network of autonomous systems?

A.
IGMP

B.
ICMP

C.
EGP

D.
OSPF

Explanation:

EGP stands for Exterior Gateway Protocol. It is used for exchanging routing information between
two gateways in a network of autonomous systems. This protocol depends upon periodic polling
with proper acknowledgements to confirm that network connections are up and running, and to
request for routing updates. Each router requests its neighbor at an interval of 120 to 480
seconds, for sending the routing table updates. The neighbor host then responds by sending its
routing table. EGP-2 is the latest version of EGP.
Answer option B is incorrect. Internet Control Message Protocol (ICMP) is a maintenance protocol
that allows routers and host computers to swap basic control information when data is sent from
one computer to another. It is generally considered a part of the IP layer. It allows the computers
on a network to share error and status information. An ICMP message, which is encapsulated
within an IP datagram, is very useful to troubleshoot the network connectivity and can be routed
throughout the Internet.
Answer option A is incorrect. Internet Group Management Protocol (IGMP) is a communication
protocol that multicasts messages and information among all member devices in an IP multicast
group. However, multicast traffic is sent to a single MAC address but is processed by multiple
hosts. It can be effectively used for gaming and showing online videos. IGMP is vulnerable to
network attacks.
Answer option D is incorrect. Open Shortest Path First (OSPF) is a routing protocol that is used in
large networks. Internet Engineering Task Force (IETF) designates OSPF as one of the Interior
Gateway Protocols. A host uses OSPF to obtain a change in the routing table and to immediately
multicast updated information to all the other hosts in the network.