Server Not Found errors when accessing some websites

I have a friend with a Windows Vista machine. When accessing certain websites like ebay, yahoo mail and craigslist, she often gets "server not found" error pages in the browser. Sometimes, clicking the link again sometimes will access the page properly, but many times it still doesn't work.
This is happening both with internet explorer AND firefox.
When other laptops on the same wireless network access the internet, none of these problems occur.
I scanned for viruses, removed all spyware and did a quick look with the Hijack-This utility. I can't find evidence of any malware causing this problem.
I also looked at the hosts file and its clean.
I would appreciate some other ideas to check into.
thanks

 

Try modifying your local DNS settings. Make sure that you are using not just the DNS servers provided by your ISP, but a third-party service as well (OpenDNS, etc, etc, etc).

These days, if your ISP or one of its connection/peering partners is making changes to prepare for an IPv6 rollout, this can affect the timely resolution of DNS queries.

 

Thanks newsposter. Just one question though. It this was a DNS server issue, wouldn't the problem be evident on all laptops that connect to the same WIFI network?

 

IF (IF!) this is related to IPv6 transition activity, it's a momentary/transitory failure of the DNS and IPv4v6 translation (address to address) to respond back to the machine in a timely manner.

It will happen at random, to differing machines and on differing networks at differing times.

Make sure that the DNS settings on your friends machine is using multiple DNS servers both internal and external to the local (ISP, campus, whatever) network.

There is a local University network that I connect with from time to time, both wired and wireless. Their internet peering recently transitioned to 100% on the i2 backbone. Great for speeds and latency. But the translation delays from certain legacy IPv4 DNS servers to the IPv6 addressing makes for a lot of random 404 errors. I've learned to deal with it. Pretty much have to until the global root DNS servers get transitioned to IPv6 themselves. Identifying local DNS servers that are running BIND v9 can help some, but only if they were set up with IPv6 in mind.

At one time there was a Vista bug that affected timely DNS lookups as well but that was fixed both as an individual kb and in one of the service packs.

 

I've heard that it's best to use DNS servers that are geographically close to my location. Whats the best strategy on finding DNS servers and their IP addresses to use.

 

Part of OpenDNS's and GoogleDNS's magic is that they automatically resolve to the closest geographical server to you. L3 is another good DNS server system.

 

The closest geographical server may NOT be the closest in terms of network hops.

The 'problem' with dynamic DNS resolution and IP forwarding is that a provider can use one IP address for all of their service worldwide and depend on router protocols to direct traffic to what they might decide is the closest device.

This kind of manipulation, while great for end-user convenience and redundancy/reliability, can play bloody hell with manual attempts to ensure the use of low hop counts to reduce response times (the all-important latency).

 

@the OP... If you're having an unusual amount of 404's, look into the local configuration. Check the WiFi router if you can, and manually put your own DNS addresses in at the source, then you won't have to change them on all the connected computers. Then try pinging some random places, or places where you usually get 404's. Look for latency issues. Usually when you get a 404, then hit refresh and get a normal page load, your packets are getting "brickwalled" or dumped somewhere, usually local. Also try this....

On all NT based Windows machines press "Windows+r" to open a Run prompt... type in "cmd" and hit enter. Now type "ipconfig /flushdns". That will clean out your local DNS cache. Now without closing the CMD window, type in "ipconfig /release" after hitting enter there you should see it release all your active IP's on all connected adapters. Now type in "ipconfig /renew" to re-lease new addresses and pull the new DNS info from the router.