4. When a machine boots and its ARP cache is empty, explain the step-by-step process through which the MAC addresses get added to the cache when the machine wants to send a packet to another host with an unknown MAC address.
This question evaluates the candidate's grasp of the ARP process from an empty cache scenario and assesses their ability to describe the sequence of actions taken by the origin host to obtain the necessary MAC address information.
The origin host creates a special Ethernet frame containing an ARP request packet for the MAC address that corresponds to the target IP address.
The origin host broadcasts the frame to the entire physical network for the target's subnet.
If one of the other hosts on the subnet knows the correct MAC address, it creates a reply packet and frame containing the IP address and sends it back to the origin. Often, the host that replies is the target host and is simply replying with its own MAC address.
The origin host adds the IP MAC address pair to the ARP cache and can proceed.
