What happens when a host receives an ARP request packet?

The ARP request is received and processed by all the hosts in the network, since it is a broadcast packet. The following steps are carried out when a ARP request packet is received by a host:

If the IP address to be resolved is for this host, then the ARP module sends an ARP reply packet with its Ethernet MAC address.

If the IP address to be resolved is for this host, then the ARP module updates its ARP cache with the source Ethernet MAC address to source IP address mapping present in the ARP request packet. If the entry is already present in the cache, it is overwritten. If it is not present, it is added.

If the IP address to be resolved is not for this host, then the ARP module discards the ARP request packet.

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