ARPl is used to dynamicly map IP addresses to physical (hardware ) addresses. ARP's use is limited to networks that support hardware broadcast. If host A was looking for host B on a network. Host A would brodcast to all networkadapters on the network a message saying I am looking for B. This would be done in IP by transmitting on eg 192.77.233.0 the last address of 0 is the broadcast address of the network. This message is read by all devices on the network. Host B responds by transmitting its MAC addrress. All other hosts dropthe message. The following are the syntax that you can use with the ARP command.ARP -a displays al the contnets of the the arp table.ARP -d inet_addr deletes the address specified by the inet_addr.ARP -n inet_addr displays all entries for the address specifid in inet_addr.ARP -s adds the host inet_addr and associates it to the physical address specified in eth_addr.
Ethernet Address Resolution Protocol, RFC 826
From: Communications

Address Resolution Protocol. Used to dynamically discover the low-level physical network hardware address that corresponds to the high level IP Address for a given host, for instance. ARP is limited to physical network systems that support broadcast packets that can be heard by all hosts on the network. See also Proxy ARP.
From: Information Technology