ITPEC FE Morning April 2018 Question 34

Unicast — the ARP reply goes straight back to the one host that asked.

ARP resolves an IP address to a MAC address in two messages:

• •Request: the sender does not know the target's MAC address, so it broadcasts "who has this IP address?" to every host on the segment
• •Response: the target learned the sender's MAC address from the request, so it replies to that host alone

Answer (d)

Why not others:

• •(a) Anycast — delivers to the nearest of several hosts sharing one address, used for services such as DNS; ARP does not use it
• •(b) Broadcast — the delivery model of the ARP request, not the response
• •(c) Multicast — delivers to a group of subscribed hosts; ARP has no group to address

Key rule: A message is broadcast only when the sender does not yet know who should receive it; once the address is known, replies are unicast.

Networks · AI-written, may contain errors