Let's search out how does a computer know whether an incoming frame have an ARP message. The type field in the frame header defines that the frame contain an ARP message. The Ethernet standard substance that the type field in an Ethernet frame carrying an ARP data packet must has the hexadecimal value 0 x 806, as given in the figure below.
CASHING ARP RESPONSES:
Although message interchange can be used to bind addresses, sending a request for every binding is hopelessly not efficient. To remove network traffic, ARP software saves and extracts the information from a response so that it may be used for subsequent data packets. ARP manages the Table as a cache short-term memory.