4 ms·

Is the dns-prefetch only useful for things that are not already linked/included on the page? (such as redirect chains... t.co links might DNS prefetch the domai

by buro9 13y ago

Is the dns-prefetch only useful for things that are not already linked/included on the page? (such as redirect chains... t.co links might DNS prefetch the domain of the end of the chain) Or is the benefit that you can start the DNS resolution whilst receiving the <head>, for the JavaScript resources only included near the </body>? (being a very slight performance benefit) Edit: And I suddenly thought... for SSL pages would dns-prefetching leak some information to an observer about the composition pf content or the linked resources on a page by grouping such DNS requests into a short burst at the same time as the SSL request?

igrigorik 13y ago
Correct on both counts.. Pre-fetching DNS names for origins not on the page is, indeed, a nice use case - redirects are a good example. Similarly, embedding a <link rel=dns-prefetch> in the head will trigger an early DNS lookup, which can, in fact, deliver big latency savings -- you would be surprised how slow DNS lookups are in practice. Last but not least, AFAIK, I'm not aware of any logic to group DNS-prefetch hints or similar strategies when running over TLS.
- pessimism 13y ago
  I tried implementing it for my blog’s pagination, but I definitely don’t see the zero-second latency Google report in the video, and it doesn’t seem any faster at all. Can you tell me if it’s actually working from using the pagination at the bottom of the front page, or the pagination inside the permapages: http://pygm.us/1e9KHCYt http://pygm.us/1e9KHCYt. (Link fixed.)
  - igrigorik 13y ago
    You can see if pre-rendering is being triggered in chrome://net-internals#prerendering. See: http://www.igvita.com/posa/high-performance-networking-in-google-chrome/#prerender http://www.igvita.com/posa/high-performance-networking-in-go... And "yes": https://www.evernote.com/shard/s1/sh/0f3592b8-d72c-40f7-9bbf-38a12b51c57e/6682c3f17808d1dcc1e4df04afc0bb7d https://www.evernote.com/shard/s1/sh/0f3592b8-d72c-40f7-9bbf...
    - pessimism 13y ago
      Any idea why the prerendering fails? http://i.imgur.com/pxijNnq.png http://i.imgur.com/pxijNnq.png http://i.imgur.com/QxcNIeO.png http://i.imgur.com/QxcNIeO.png Thanks for the help, by the way. :)
  - deleted 13y ago
    [deleted]

by buro9 13y ago

igrigorik 13y ago

Correct on both counts.. Pre-fetching DNS names for origins not on the page is, indeed, a nice use case - redirects are a good example. Similarly, embedding a <link rel=dns-prefetch> in the head will trigger an early DNS lookup, which can, in fact, deliver big latency savings -- you would be surprised how slow DNS lookups are in practice. Last but not least, AFAIK, I'm not aware of any logic to group DNS-prefetch hints or similar strategies when running over TLS.

pessimism 13y ago
I tried implementing it for my blog’s pagination, but I definitely don’t see the zero-second latency Google report in the video, and it doesn’t seem any faster at all. Can you tell me if it’s actually working from using the pagination at the bottom of the front page, or the pagination inside the permapages: http://pygm.us/1e9KHCYt http://pygm.us/1e9KHCYt. (Link fixed.)
- igrigorik 13y ago
  You can see if pre-rendering is being triggered in chrome://net-internals#prerendering. See: http://www.igvita.com/posa/high-performance-networking-in-google-chrome/#prerender http://www.igvita.com/posa/high-performance-networking-in-go... And "yes": https://www.evernote.com/shard/s1/sh/0f3592b8-d72c-40f7-9bbf-38a12b51c57e/6682c3f17808d1dcc1e4df04afc0bb7d https://www.evernote.com/shard/s1/sh/0f3592b8-d72c-40f7-9bbf...
  - pessimism 13y ago
    Any idea why the prerendering fails? http://i.imgur.com/pxijNnq.png http://i.imgur.com/pxijNnq.png http://i.imgur.com/QxcNIeO.png http://i.imgur.com/QxcNIeO.png Thanks for the help, by the way. :)
- deleted 13y ago
  [deleted]