Get GTmetrix to use a custom DNS when performing tests.

There are a number reasons why you may need GTmetrix to use a custom DNS:

• Redirecting development/staging sites to the production site’s real hostname
• Accessing geoblocked resources
• Blackholing resources to test for affects on overall performance

With our Override DNS feature, you can now specify a hostname and IP address to ensure your site is analyzed how you need it to.

Override DNS is only available with the Developer Toolkit.
 

What does Override DNS do?

In simple terms, a DNS acts like a phone directory between domain names and IP addresses.

For example, typing in facebook.com in your address bar would send that domain to a DNS server, which would then route it to something computers understand better, like an IP address (in this case, 31.13.69.228).

A local DNS looks up hostnames and matches them to their corresponding IP address for computers to understand better.

Most DNS servers are operated by Internet Service Providers (ISPs) who keep them updated constantly. However, there are occasions where you may want to domain name to be routed differently – this is where a custom DNS would be useful.

Overriding your DNS would essentially tell domain names to go to IP addresses you designate, and not what the general DNS servers would typically define.

Overriding a DNS lets you tell GTmetrix where to go instead of the proper destination.

GTmetrix simply provides the ability to override hosts and IP addresses to direct them to your desired server.

How to use it

To override your DNS, enter a URL into the Analyze field, and expand the Developer Tookit in the Analysis Options.

The Developer Toolkit is located in the Analysis Options on the Dashboard.

Click “Add a Custom DNS” under the Override DNS section – A Host field and IP Address field will appear.

Add as many custom DNS’s as needed.

Input the host and IP address corresponding to your custom DNS – for example:

Host Name: facebook.com
IP: 12.34.56.78

When you analyze your page, GTmetrix will use the custom DNS settings you’ve inputted.

Note: Sites using https:// and SSL will still require the newly pointed server to have their SSL certificate properly set up, or GTmetrix will be unable to analyze.

Save it as a Preset!

For convenient access, be sure to save your custom DNS as a preset.

Create a custom DNS preset for quick analysis .

Learn more about how to use GTmetrix analysis presets.