How do I clear the ARP cache?

The Microsoft Windows ARP cache will occasionally become corrupt and need to be cleared.

The first symptom you are likely to notice is that connections to web pages will time out and fail.

If you troubleshoot further, you will notice that you can `ping` your IP address and also 127.0.0.1, but not other IP addresses.

Clearing the ARP Cache

To fix this error, you will need to clear the ARP cache. This is done with the `netsh` command:

C:\>netsh interface ip delete arpcache
Ok.

Viewing the ARP Cache

If you would like to view your ARP cache, this can be accomplished using the `arp` command:

C:\>arp -a

Interface: 192.168.1.100 --- 0x10004
 Internet Address      Physical Address      Type
 192.168.1.1           00-0f-66-37-22-32     dynamic

If Clearing the ARP Cache Fails

Occasionally, clearing your ARP cache will fail due to a bug in Microsoft Windows.

If you try to use Microsoft Windows to repair the network connection, you will receive an error message that says:

Windows could not finish repairing the problem because the following operation could not be completed:
Clearing the ARP cache
For assistance, contact the person who manages your network

This bug occurs when Routing and Remote Services is enabled. Routing and Remote Services is almost unnnecessary and can be turned off unless you know that you are using it.

To disable Routing and Remote Services:

• Click the button
• Click the button
• Switch to "Classic View" if you are in "Category View"
• Click
• Click
• Double-click
• Double-click
• Scroll down to
• Double-click
• Examine the "Startup Type"
• The options are "Automatic", "Manual", and "Disabled"
• Set the "Startup Type" to "Disabled"
• Examine the "Service status"
• Make sure that the service status is Stopped. If it is not Stopped, click the button
• Click the button

Now, try clearing the ARP cache again and it should complete with no error messages.

Extracted from http://www.tech-faq.com/clear-arp-cache.shtml