Disable DNS and HTML5 Link Prefetching in Firefox

Mozilla Firefox uses prefetching technologies to speed up your browsing experience by loading web pages and resolving domain names in the background before you actually click on a link. While this reduces loading times, it also generates unsolicited network requests that can compromise your privacy and consume unnecessary bandwidth. This article provides a straightforward guide on how to access Firefox's advanced configuration page to completely disable both HTML5 link prefetching and background DNS prefetching.

Accessing Firefox Advanced Preferences

To change how Firefox handles network requests, you must first access the browser's hidden configuration editor.

  1. Open the Firefox web browser.
  2. Type about:config into the address bar and press Enter.
  3. A warning page will appear. Click the Accept the Risk and Continue button to proceed to the preferences search page.

Websites use HTML5 link prefetching to tell your browser which pages you are likely to visit next, prompting Firefox to download those pages in the background.

  1. In the about:config search bar at the top, type or paste network.prefetch-next.
  2. Locate the preference in the results list. By default, its value is set to true.
  3. Double-click on the network.prefetch-next row, or click the toggle icon on the far right, to change its value to false.

Disabling Background DNS Prefetching

DNS prefetching causes Firefox to proactively perform domain name resolution on links found on the current webpage. Disabling this ensures Firefox only resolves domains when you explicitly click a link.

  1. Clear the about:config search bar and type or paste network.dns.disablePrefetch.
  2. Double-click the preference or click the toggle icon to change its value from false to true.
  3. Next, search for network.dns.disablePrefetchFromHTTPS to ensure DNS prefetching is also blocked on secure websites.
  4. If the value is set to false, toggle it so that it reads true. (If this preference does not exist in your version of Firefox, select the Boolean radio button, click the + icon to create it, and set it to true).

Once you have adjusted these values, simply close the about:config tab. The changes take effect immediately, and Firefox will no longer make unsolicited DNS or link prefetching requests in the background.