How to Test DNS Cache

The Domain Name System (DNS) is how computers see website addresses. We see, for example, www.yahoo.com, but the computer sees the actual IP address. DNS allows us to type in the web address instead of typing in the IP address. Using the nlookup command will test the DNS cache.

• 1

  Click "Start," type "cmd" in the search bar and press "Enter." A black window will open. At the command prompt type "cd\windows\system32" and press "Enter" to change the directory.

• 2

  Type "nslookup" and press "Enter." The DNS server settings will display on the screen. Type www.google.com (or any website address) and press "Enter." You will see the IP address for the website you entered. An IP address looks something like 555.123.393.49.

• 3

  Type "ping -a (the above IP address for the website you entered)" and press "Enter." For example, it may look something like "ping -a 312.079.114.74." Make sure the -a switch is in front of the IP address you use. In the results, verify that the DNS server successfully sent and received packets. For example, it may say "Sent = 4, Received = 4, Lost = 0." If so, the DNS cache on the computer is correct.