Applied Test Series

Question

A PC has just booted up and wants to communicate with a host on a remote subnet. The PC knows the IP addresses of its default gateway and the remote host. However, in order to properly construct a frame, the PC needs an appropriate destination MAC address. What MAC address does the PC need to learn, and what protocol will the PC use to learn that MAC address?

 

Answer 1

Source and destination MAC addresses are rewritten at each router hop along the path from the source to the destination (if the router interface is Ethernet-based). Therefore, the frame sent by the PC should have a destination MAC address of the PC’s default gateway (i.e. the PC’s next-hop router). However, the source and destination IP addresses do not change (unless some other service, such as Network Address Translation (NAT), is in use). The PC can learn the MAC address of its default gateway using ARP (Address Resolution Protocol). While ARP provides IP address to MAC address translation, DNS (Domain Name System) provides domain name to IP address translation.

 

 

The MAC address of the PC’s default gateway learned via ARP is the most suitable answer for this question.