Multiple dns lookups

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+1 Q:

Multiple dns lookups

I just ran a load time analysis for a website. The results can be seen here:

http://gtmetrix.com/reports/www.parship.co.uk/VfLleffe

When you check the timeline you will see that some images have a dns lookup time and some do not. Even when the images are on the same subdomain some require a dns lookup and some do not.

Is this totally random? Or is there a way to prevent multiple dns lookups for the same subdomain?

Thanks...

That's a simple answer - if you reference the images in your html with the site's domain name it will trigger a DNS lookup.

This will not trigger a DNS lookup:

<img src="/logo.png" alt="Site Logo" />

This will trigger a DNS lookup:

<img src="http://www.mysite.com/logo.png" alt="Site Logo" />

Peter Hanneman 2010-07-12 12:59:20

References for this alleged behaviour? I've seen YSlow report similar even when all links were relative.

Alnitak 2010-07-12 14:12:24

I'll go try to find some but I've seen this from personal experience. Are you using a "/" in front of some of the images and not others? Have you tried setting the base tag in the html header?<base href="www.mysite.com/sitedir/"></base>

Peter Hanneman 2010-07-12 19:02:09