Address Resolution Protocol (ARP) is a protocol for mapping an IP address to a physical machine address that is recognized in the local network. The physical machine address is also called Media Access Control or MAC address. A table, usually called the ARP cache, is used to maintain a correlation between each MAC address and its corresponding IP address. ARP provides the protocol rules for making this correlation and providing address conversion in both directions.
ARP is very crucial for TCP/IP network communication. If you begin to notice network connectivity problems such as particular web pages not loading or not being able to ping certain IP addresses then clearing your ARP cache is a good place to start. The TCP/IP ARP Command component provides the functionality to add, delete, or display the IP address for MAC address translation.
To flush/Delete the ARP cache in Windows 2000/2003, run the following command;
netsh interface ip delete arpcache
Delete IP address using arp command
arp -d <ip address>
Display arp table
Add static entry to ARP table
arp -s <ip address> <mac address>