How To Clear the ARP Cache in Windows XP, Vista and 2003

When diagnosing a network problem, you may get the error "Windows could not finish repairing the problem because the following operation could not be completed: Clearing the ARP cache".

To clear the ARP cache in windows Vista, XP or Server 2003 follow these directions.

• Click on Start, click on Run and type cmd and press enter.
• In the command prompt box type "netsh interface ip delete arpcache"
  
  

So what is the ARP cache?

Address Resolution Protocol (ARP) is is a component of TCP/IP network communication. ARP provides the functionality to add, delete, or display the IP address for Media Access Control (MAC) address translation.

The ARP cache is designed to reduce the number of address resolution requests, a client normally caches resolved addresses for a predetermined period of time. The arp cache is of a finite size, and would become full of incomplete and obsolete entries for computers that are not in use if it was allowed to grow without check. The arp cache is therefore periodically flushed of all entries. This deletes unused entries and frees space in the cache. It also removes any unsuccessful attempts to contact computers which are not currently running.