Clearing the Address Resolution Protocol Cache

There are many inner workings required for computers to run correctly. Many of these inner workings occur without the average user ever knowing that they are taking place. Windows tries its best to ensure that you never need to peek behind the curtain and that your computer will run properly without you needing to know about these items.

One such area is what is known as the Address Resolution Protocol (ARP) cache. Without getting too technical, ARP is used to track an IP address back to a specific device in a local area network (LAN) by converting the 32-bit IP address to the 48-bit Media Access Control (MAC) address that is unique for each device. What this means is, when you enter an IP address such as 192.168.0.1 (a default IP address for many wireless routers), your computer will connect to the correct device. If that all sounds complex, think of ARP as a data guide for your computer.

As with many things on your computer, Windows speeds things up by maintaining a list or a cache of commonly used ARP-to-MAC references. Caches speed things up by being referred to quickly, rather than creating a new translation each time. Typically, your computer tries to clear caches at various times, perhaps when you close a program, plug something in, or when restarting your machine. However, sometimes these caches can become inundated with errors or unwanted entries that may not be removed automatically. When this happens, you might begin experiencing network connection issues. Fortunately, Windows makes clearing out the ARP cache easy. (The process of clearing your ARP cache is referred to as "flushing the ARP cycle.")

The first thing you need to do is make sure that the "Routing and Remote Access" service is stopped. To do this:

1. Press Windows+R to open the Run prompt.
2. Type (without quotes) "services.msc" then press Enter. This opens the Services window.
3. In the list of services, locate the "Routing and Remote Access" service. Right-click on the service and select Properties from the Context menu. This opens the Routing and Remote Access Properties window.
4. On the General tab, next to Service Status, ensure it says "Stopped." If it doesn't say it is stopped, click the Stop button, and then OK.
5. Close the Routing and Remote Access Properties window.

Now you can proceed to actually flush the cache. To flush the ARP cycle, we need to run a command in Command Prompt.

1. Press the Windows key and type (without quotes) "CMD." In the results window, choose the Run as Administrator option. Windows opens a Command Prompt window.
2. Enter one of the following commands and then press Enter.

arp -d

or

netsh interface IP delete arpcache

3. Close the Command Prompt window.
4. Restart your computer.

When your computer restarts, it will create a new ARP cache. This should help any ARP-related issues that your computer was having.

 This tip (9137) applies to Windows 10 and 11.