DNS Prefetching

Despite anchor tags having HREF attributes which lead to other host names, browsers do not execute DNS lookups on those domains. Content prefetching can be invaluable in speeding up your websites, but did you know that you can also implement DNS prefetching? It's as easy as simple LINK element:

<link rel="dns-prefetch" href="//somehost.tld" />

This technique can be very useful when your website links to related host names. Take Twitter for example; they implement two DNS prefetches:

<link rel="dns-prefetch" href="https://si0.twimg.com" /> <link rel="dns-prefetch" href="https://api.twitter.com" />

I'd be willing to bet that most of you didn't know this tag existed. It's an interesting idea with a very simple execution. What do you think? Do you manage websites that prefetching could be helpful for?