Enterprise Software

Chrome DNS shortcut revealed

The Chromium Blog has detailed one of the shortcuts that Google Chrome uses to enhance the browsing experience: DNS prefetching.

The Chromium Blog has detailed one of the shortcuts that Google Chrome uses to enhance the browsing experience: DNS prefetching.
 
When a user visits a website in Chrome, the browser will scan for unvisited domain names and will automatically resolve them to an IP address. Google claims that on average this process saves the user about 250ms.
 
As for how the users' view this feature, the blog says:
"Humorously, this prefetching feature often goes unnoticed, as users simply avoid the pain of waiting, and tend to think the network is just fast and smooth. To look at it another way, DNS prefetching removes the variance from surfing latency that is induced by DNS resolutions."
 
You may have had someone saying "it just feels faster" when they first tried Chrome, well now you have one reason why that was so.
 
To view what Chrome is up to, you can type "about:dns" in the address bar.

A snippet of the type of results that "about:dns" produces.


 
To see the timings of name resolution, type "about:histograms/DNS.PrefetchFoundName", in fact, "about:histograms" has a few graphs if you are really curious.
 

An example of the prefetch histogram.



If you think that prefetching sounds familiar, that's because Mozilla has a link prefetching option, but it is an entirely different kettle of fish. Link prefetching grabs entire pages as directed by website authors, whereas Chrome auto-magically does DNS prefetching.
 
For those people waiting for a Web OS, this humorous article also provides a little reality check.

About Chris Duckett

Some would say that it is a long way from software engineering to journalism, others would correctly argue that it is a mere 10 metres according to the floor plan.During his first five years with CBS Interactive, Chris started his journalistic advent...

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