The address resolution protocol (arp) is a protocol used by the Internet Protocol (IP), specifically IPv4, to map IP network addresses to the hardware addresses used by a data link protocol.
For example, consider the below topology
From the above topology, we can understand that all the computers are connected to a single network.
When a device 192.168.1.3 connects to the network for the first time there is no MAC address of that particular machine on the arp table.
If 192.168.1.2 wants to send any data or to check the connectivity, the packet is broadcasted to all the interface of the switch, and the packet would look like this.
The PC doesn't know the MAC of the 1.3 PC so the destination field is not and for that reason in the place of destination MAC FFFF:FFFF:FFFF is used.
FFFF:FFFF:FFFF is used for broadcasting purposes.
Once the packet frame reaches all interface the device would check for the IP address and if it matches they would reply to the request according to the type of the request.
The ARP reply would be unicast.
Once the machines receive the reply than the address will be stored on the Arp table.
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