How to troubleshoot "Server not found" messages while browsing?

How to troubleshoot "Server not found" messages while browsing? On my Mac with OS X Snow Leopard, I continually get "Server Not Found" errors on my web browser (Firefox) while browsing various web sites. In attempts to resolve the problem I've tried the following (each, more than once):
Asked by: Guest \| Views: 203

Total answers/comments: 3

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Guest [Entry]

Whether right or not, I ended up replacing my wireless router. It seems to have resolved the issue.

Guest [Entry]

"This is a know issue, there is a bug in mDNSResponder (there are plenty of posts in discussions.apple.com), some others already opened a bug in Apple, we don't know if they will deliver it in 10.6.3, as this bug is not massive, but depends on the ISP's DNS server (even if you set the OpenDNS servers, it will not change the situation, as a second bug in mDNSResponder mess up with the order of DNS servers it has in list, and even if you ""force"" it to use the OpenDNS, it will get the one ""offered"" by the default gateway, which is the one provided by your ISP, which is the one matching with the first bug). I have the some problem and there is no solution at the moment, downgrade to Leopard or wait for 10.6.3 (...or ask your ISP to change/update their DNS Server)...

Another alternative is to create ""in LAN"" a proxy... in that way it should work (it seems for someone, as you will see from the posts in discussions...). I'll wait 10.6.3 even if I'm not sure they will fix it 100%, are a couple of tricky bugs and not easy to replicate and solve.

bye
gpy"

Guest [Entry]

"I'm having the same problem on my Snow Leopard macbook (10.6.8). Occasionally Firefox can't find the server, nor can ping, but nslookup resolves the IP. I only recall having the issue with en.wikipediadotorg.

Here's something that worked 2 or 3 times for me so far for en.wikipediadotorg:
Visit www.wikipediadotorg and click on ""English"" which takes you to en.wikipediadotorg. This makes the host ""reappear"" immediately. (Before I tried this, it would take about a minute for the host to be recognized again.)

I tried a similar workaround by google'ing for the site and clicking the link from the search results, but it didn't work. Maybe it's related to a cache being cleared only when another host on the same domain is accessed."