Comments on: Sharding Dominant Domains

By: Brendan Gibson

Brendan Gibson — Fri, 04 Mar 2011 21:34:47 +0000

Thanks Steve. I’ll see if we can do some of our own tests on this and feed the results back into the community.

By: Steve Souders

Steve Souders — Fri, 04 Mar 2011 02:21:06 +0000

@Brendan: Since newer browsers open more connections per domain, it’s probably better to revise the number downwards. I think 2 is a good compromize, but that’s just a hunch. It’d be great if some production property ran a test to determine the optimal number.

By: Brendan Gibson

Brendan Gibson — Thu, 17 Feb 2011 17:57:57 +0000

This article was written two years ago when IE7 may have been the dominant browser. Now that the proportions of browser usage has changed, do you think we need to revisit the optimal number of domains? And revise it upwards?

By: Steve Souders

Steve Souders — Fri, 30 Apr 2010 13:57:56 +0000

@Guillermo: The best test is to do a test on your live traffic with JavaScript timing the page (see the Jiffy Web project).

@Matt: You can look at the source code and see that these are the correct settings.

@Michael: I have not tested ports. It would be great if you created a test page with a bunch of images from different ports, and then watched them in Firebug Net Panel to see if the number of parallel connections exceeds the max. Please comment back here if you do so.

By: Michael

Michael — Fri, 30 Apr 2010 09:05:24 +0000

Will domain sharding work if I serve images from different TCP ports?

By: Matt

Matt — Tue, 13 Oct 2009 15:23:52 +0000

“Not all browsers are restricted to just two parallel downloads per hostname.”

How sure are you about that? My impression was that installing IE8 raises the simultaneous connections limit by changing a system-wide setting.

Have you tested Firefox or Chrome on a fresh install of Windows that’s never seen IE8?

By: Guillermo Quintana

Guillermo Quintana — Fri, 22 May 2009 05:28:34 +0000

I’ve been doing quite a bit of research regarding domain shredding. Is there a tool or method i could use ( short of proto-typing) to test using 2 vs. 4 host manes for static images across my website? My testing is limited to only http requests as i would prefer to leave all of my assets for ssl under a single hostname

By: Éric

Éric — Tue, 19 May 2009 10:37:15 +0000

Also, for SSL the cost of a new connection is higher, so having to much domain / to much connections could be negative far more quicker than with non-ssl domains.

With new browers that have 6 threads per domain, it’s probably safe to stay with only one domain on SSL (and never more than two).

By: Party Ark

Party Ark — Mon, 18 May 2009 19:48:15 +0000

Good article – on thing to remember, however, is NOT to implement this technique for SSL (https) unless you’re able to secure ALL the ‘sharded’ subdomains. There are certificates that can handle multiple subdomains, but most don’t. And if you don’t have one, your user will end up with all sorts of warning messages about mixed resources and a broken ‘padlock’ symbol.

By: Martin Borthiry

Martin Borthiry — Thu, 14 May 2009 14:09:08 +0000

Great article!

I think that in some cases could be possible to check the browser type and define dynamically the number of hostnames. The script has a time cost, but it reduce the DNS lookup time for newest browsers.