Real Clear Computing

Windows ARP Command – Display and Clear ARP Cache

The following tutorial explains how to use the arp command in Windows to view and clear the ARP cache.

The Windows operating system maintains an ARP Cache—A table that contains the recent mappings of IP addresses to MAC addresses. The arp command is the Windows command we use to view and modify the ARP table.

Command Options

The Windows arp command has only a couple of options: -a to view the ARP cache and -d to clear the ARP cache.

-aUse this option to display the ARP table.
-dUse this option to clear the ARP cache.
-sUse this option to add manual entries to the ARP table.

You can run the arp command from both CMD and Windows PowerShell.

Display ARP Table

To view the ARP cache on a Windows system, run the following command:

arp -a

Running arp -a on Windows shows output similar to the following:

view windows ARP cache

If the computer has multiple network interfaces, you will see an ARP table under each interface. We can view the ARP table of a specific interface with the -N option by specifying the IP address of the NIC.

arp -a -N 192.168.1.245

Clear ARP Cache

To clear the ARP cache, we use the -d option, as shown in the following example:

arp -d

The above command deletes all entries from the ARP table. To delete a single entry from the table, specify the IP address of the destination host, as shown in the following example:

arp -d 10.0.0.10

In the above example, the arp command deletes the MAC address associated with host 10.0.0.10.

clear arp cache

Add a Static Entry to the ARP Table

The -s option of the Windows arp command allows administrators to add manual entries to the ARP cache. To add a static entry, you will run the arp command as follows:

arp -s 10.0.0.20 00-aa-00-62-c6-09

In the arp -a output, static entries are marked as "static" in the type column.

arp command windows

Address Resolution Protocol

ARP stands for Address Resolution Protocol. It is a TCP/IP protocol that resolves the MAC address of a destination host.

When the host_a needs to send a packet to host_b, it needs to know the MAC address of host_b. If host_a does not know the MAC address of host_b, it will send a broadcast message to the network asking for the MAC address (all devices in the local network receive this message).

Once the broadcast message is received, host_b responds to host_a with its MAC address. This process is known as Address Resolution.