DNS resolution errors, site is unimportant. This happens from Netflix, Hulu to even here. I have changed my router from using the DNS provided by SBC DSL to Google's. The problem still persists. I can provide a temporary fix with the Windows machines if I flush the computer's DNS cache. This "fix" affects both Win7 and Win2008 Server R2. I have performed checks on my cables and through the network devices, all appears well. I've had this provider for a few years and this just started a couple of months ago. This would make more sense if it was a problem across the board but it is not. It normally only affects one to two websites at a time. All equipment is even behind a UPS.
Any thoughts or ideas?
Network parts
D-Link DIR-655 hardware version B1 firmware 2.10NA
Are you over-riding your ISPs DNS services by inputting your choice of DNS servers into your router?
Remove the chosen DNS servers from you router, just to see if the problem persists. If they do not, you could phone your ISP and see if they wont run DNS services on your line.
If the do, it is likely your main router is starting to die or is overloaded with too many network devices connecting to it.
I have been running this network in it's current form for roughly 18 months. I was originally using the ISP's (ATT) DNS and started having this current problem. The DNS not fetching is actually much worse on their DNS opposed to using the one from Google. No devices have been added to the network, in fact I dropped one device (dish network dvr) about 5 months ago.
This problem has been steadily getting worse. I have tried running directly from the DSL modem and in most cases this seems to help dramatically. What is strange is I cannot get any errors to occur with any standard software to measure this. Now I am testing about a dozen changes to my router configuration and for the first day it seemed to help. A few days later I am experiencing some of the same problems to a lesser degree.
It looks like I may be due to upgrade this router. We are after all talking about a D-Link DIR-655. I guess it is showing it's age and maybe wear due to very high use levels.