ARP table
The ARP table is a construct that is maintained within all network devices running IPv4 over a Layer 2 network technology such as Ethernet. The ARP table maintains an IP address to Layer 2 address mapping. When used with Ethernet, this is an IP address to MAC address mapping. A fully populated ARP table on a host contains the IP address to MAC address mappings of all IP addresses within the host's subnet.
All network devices that have an IP address including hosts, routers, switches, printers, IP cameras, wireless clients etc... maintain an ARP table.
On a Windows device, the ARP table can be viewed using the following command:
C:UsersH1>**arp -a** Interface: 192.168.1.1 --- 0xb Internet Address Physical Address Type 192.168.1.2 00-0c-29-63-af-d0 dynamic 192.168.1 .255 ff-ff-ff-ff-ff-ff static 224.0.0.22 01-00-5e-00-00-16 static 224.0.0.252 01-00-5e-00-00-fc static 239.255.255.250 01-00-5e-7f-ff-fa static 255.255.255.255 ff-ff-ff-ff-ff-ff static
The following is an example of an ARP table from a Cisco IOS device:
Router# show ip arp Protocol Address Age(min)Hardware Addr Type Interface Internet 171.69.233.22 9 0000.0c59.f892 ARPA Ethernet0/0 Internet 171.69.233.21 8 0000.0c07.ac00 ARPA Ethernet0/0
ARP entries are maintained within the table for a specific amount of time