Explain why the Telnet session was established to one of the hosts with the duplicate address and not the other. Explain why the Telnet session was established at all and did not result in an error message. Use the ARP cache and the captured packets to support your explanation.

Question

What will be an ideal response?

Answer 1

When a host tries to establish telnet connection, it first checks its to see if the host with which it is
trying to establish telnet connection is present in the ARP cache. If there is no cache information,
then an ARP request is broadcasted through the network. Here there are two hosts(PC1 & PC4) with
the same IP address. PC3 receives an ARP reply from PC1 first and hence establishes the telnet
connection. PC4’s ARP response which comes in later is ignored by PC3 (determined by checking
the ARP cache). There is exactly one telnet session and that is between PC3 and PC1. Henceforth
whatever IP datagrams are sent by PC3 will uniquely identify PC1 as they will contain both the IP
address and MAC address of PC1, PC4 will not read the packets as the destination MAC address of
the IP datagrams will not match with its own and there will not be any errors.
!
[12828|262x499](upload://cGZ4wuaZlutR8da78ULVKl0iOM.png)