Q1

On an Ethernet LAN, Host A wants to send an IP packet to Host B (same subnet). Which protocol does A use to learn B’s link-layer address?

1. DHCP
2. DNS
3. ARP
4. ICMP

C) ARP is right. ARP maps an IP to a MAC on the same LAN so A can build the Ethernet frame.

Q2

ARP request and reply use which destination MACs?

1. Request = unicast, Reply = unicast
2. Request = broadcast, Reply = unicast
3. Request = broadcast, Reply = broadcast
4. Request = unicast, Reply = broadcast

B) broadcast / unicast. ARP requests go to ff:ff:ff:ff:ff:ff so anyone with the target IP can answer; the reply goes straight back to the requester.

Q3

Pick the true statement:

1. IP addresses identify interfaces on a link; MACs are for routing across networks
2. MACs identify interfaces on a link; IPs are for routing across networks
3. Both IP and MAC are only local to a LAN
4. Both IP and MAC are globally routed