Dynamic address resolution is usually implemented using a special protocol.
A device that knows only the n/w layer address of another device can use this protocol to request the other device’s h/w address.
LAN Switch Device C IP address: IPC H/W address: #46 Device A IP address: IPA H/W address: #43 Device B IP address: IPB H/W address: #79 Device D IP address: IPD H/W address: #48 Who is IPB? IPB is #79
In the previous device A has to send the data to device B but knows only its IP address (“IPB”),and not its H/W address. A broadcast request asking to be send to the H/W address of the device using the IP address “IPB”.B responds back to A directly with the H/W address.
ARP is a relatively simple request/reply protocol.The source device broadcasts an ARP request looking for a particular device based on it IP address.The device responds with its h/w address in an ARP reply message.