iMac 'DNS' Issue?

Hi,

We seem to be having problems with our iMac once it wakes up from sleep mode.

The symptoms appear to be that of a partially working DNS.

As an example this morning, emails are coming in, I can connect to Facebook and Google, but most of my other bookmarks are just timing out.

This even applies to the bookmark for the sky hub (SR102), which is saved with a URL of its IP address.

Rebooting the router does not resolve the problem, but rebooting the iMac does.

Not sure what to try next other than doing the normal reboot of the iMac to resolve it.

Any ideas?

Have you flushed the DNS ?

http://coolestguidesontheplanet.com/clear-the-local-...

As previous person says flush DNS. This in effect is what happens when you reboot computer.
However this information stays on computer when you reboot router.
There appears to be a problem with the SR102 see link below.which may have answer.
http://helpforum.sky.com/t5/Archived-Discussions/SR1...
I never let my computer sleep, rather reboot, so problem would not occur

I just realised I never had that problem with my iMac and the sky sr102 but it just occurred to me that I'm using OpenDNS app which worked very well so far.

Yep. Tried that. No difference.

Still can't quite get my head around what it's doing. Can't be a real DNS issue as it's unable to connect to the router URL, which is an IP address.