Question

typed please!

5. Explain the steps/Sequence of events (in detail) that would occur if a host has packets destined for: a) A local address included in the "host"ARP table b) A local address not included in the "host" ARP table c) A address not on the "host" network

Answer 1

Nice question.. this question will clear your most of the doubts.

A)

If a host is having a packet that has the local address of destined host...

What does host do is whenever there is some packet it will directly goes to router. Router first checks the ip of the packet and decides whether to forward it to some other router or send it to the same network.. suppose the network is same then router will check its ARP table and if there is a entry that packet is unicasted to that destined host.

B) if there is no entry in the ARP table then router will broadcast the message to all the devices in the network asking one of the device to send it's physical address and when the reply came router will update its ARP table and send the packet based on the physical address. Note ARP request packet is broadcasted packet while reply is unicasted.

C) when the IP address is of different network then router wil forward it to some other router based on respective routing protocols until they get the same network in which destined host resides . On reaching the destined network either router will find physical address of host in its ARP table or it will send request packet to all the hosts to get physical address.