Which of the following is an exterior gateway protocol that communicates using a Transmission

Control Protocol (TCP) and sends the updated router table information?

A.
IGMP

B.
IRDP

C.
OSPF

D.
BGP

Explanation:

Border Gateway Protocol (BGP) is an exterior gateway protocol. It communicates using a
Transmission Control Protocol (TCP) and sends the updated router table information. The best
path is chosen on the basis of cost metric associated with the route. It is used between gateway
hosts in a network.
Answer option C 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.
Answer option A is incorrect. IGMP stands for Internet Group Management Protocol. IGMP is a
communication protocol that is used to manage the membership of Internet protocol multicast
groups. It is an integral part of the IP multicast specification. Although it does not actually act as a
transport protocol, it operates above the network layer. It is analogous to ICMP for unicast
connections. It is susceptible to some attacks, so firewalls commonly allow the user to disable it if
not needed.
Answer option B is incorrect. ICMP Router Discovery Protocol (IRDP) uses Internet Control
Message Protocol (ICMP) router advertisements and router solicitation messages to allow a host
to discover the addresses of operational routers on the subnet.It basically consists of 2 message
types used for discovering local routers. The message type 9 is sent periodically or on request
(using a message of type 10) to the local subnet from the local routers to propagate themselves.
On boot, the client may send an ICMP message of type 10 to ask for local routers. When a client
receives a message type 9, they add the router to their local routing-table.