ARP Command – Address Resolution Protocol
ARP command can display and modify the IP-to-Physical address translation tables used by address resolution protocol.
View the contents of the local ARP cache table
ARP -a [inet_addr] [-N if_addr] [-v]
Add a static Arp entry for frequent accessed hosts
ARP -s inet_addr eth_addr [if_addr]
Delete an entry
ARP -d inet_addr [if_addr]
Display current ARP entries. May include more than one network interface. If inet_addr is specified, the IP and Physical addresses for only the specified computer are displayed.
|-g||Same as -a.|
if_addr Display the ARP entries for the network interface specified by if_addr.
inet_addr Delete the host specified by inet_addr or wildcard * will delete all hosts.
Add the host and associates the Internet address inet_addr with the Physical address eth_addr.The Physical address is given as 6 hexadecimal bytes separated by hyphens. The entry is permanent.
|eth_addr||Specifies a physical address.|
If present, this specifies the Internet address of the interface whose address translation table should be modified. If not present, the first applicable interface will be used.
If two hosts on the same network(Subnet) cannot ping each other, try using ARP -a to list the addresses on each computer to see if they have the correct MAC addresses.
A host’s MAC address can be checked using IPCONFIG. If another host with a duplicate IP address exists on the network, the ARP cache may have had the MAC address for the other computer placed in it. ARP -d is used to delete an entry that may be incorrect.
ARP command to display the ARP cache tables for all interfaces:
C:\> arp -a
ARP command to display the ARP cache table for the interface on IP address 10.0.0.5
C:\> arp -a -N 10.0.0.5
Add a static ARP cache entry on IP addr 10.1.1.5 to the physical address 00-AA-21-5A-3A-7B
C:\> arp -s 10.1.1.5 00-AA-21-5A-3A-7B