Update 1/29/18: The Asynchronous DNS feature has been reverted due to an unspecified bug.
Chrome for Android will soon support DNS prefetching, a technology that allows for faster web browsing, according to a merged commit in the Chromium Gerrit.
DNS prefetching, which is also known as asynchronous DNS, has existed as a flag in desktop Chrome since 2012, when it was introduced as an experimental feature and disabled by default. Since then, it’s gotten some development attention, and in some cases can now cut page loading times by a few seconds.
Here’s how it works: When you visit a webpage using any web browser, your browser queries a Domain Name Server (DNS) to get the IP address of that webpage. It’s to eliminate the need to remember IP address numbers for different websites — imagine having to type “209.85.203.94” into your browser’s URL bar every time you wanted to visit Google! It’s impractical, and a much easier alternative is assigning names to web pages and having those names resolve back to an IP address.
DNS servers around the world keep a database of websites and their associated IPs, but there’s a problem: When you’re browsing the web, the DNS lookup process can take a few whole seconds in some cases. That leaves folks with perfectly capable connections waiting for servers to finish name resolution and return a website’s IP address, which is where Chrome’s asynchronous DNS feature comes in.
With the DNS prefetching flag in Google Chrome on Android enabled, Chrome scans the page for clickable links and resolves the URLs to IP addresses. By the time you head to any of the pages, their addresses will have been returned to your device, mitigating any DNS speed issues — the only bottleneck will be your own connection. (Optionally, it will use your device’s own DNS servers and won’t touch Google’s unless you want it to.)
DNS prefetching should be coming to the stable branch of Google Chrome for Android soon.
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