Certain Airport setting is keeping me from some webpages.

Question

I originally posted this thread in the Safari forum but I found out that the problem isn't with Safari it's with how Airport is connecting to the internet.
Here is a link to the original thread: http://discussions.apple.com/thread.jspa?threadID=1625722&stqc=true
Here are the important parts copied and pasted from that thread:
It only began to happen recently. The pages in question are www.eve-online.com and www.photobucket.com. I had previously been able to access both sites. In fact, I visited the former just two days ago, and now I can't access it at all. On other computers in this house - other macs and pcs - the websites load just fine even now. This leads me to believe that the problem originates somewhere with my computer. The problem happens on both Safari and Firefox.
I have tried clearing all caches, resetting all browsers, restarting browsers, reinstalling browsers, disabling firewall... I don't know what else to do.
The tabs of the offending pages read "Page Load Error" and in the body of the page there is the text
Address Not Found
Firefox can't find the server at www.photobucket.com.
The browser could not find the host server for the provided address.
followed by useless suggestions.
Any help is much appreciated! Thanks
I just had a breakthrough! Check it out..
A week or two ago I had some problems connecting to the internet. I was finally able to solve the problem by manually entering in IPv4 addess, Subnet Mask, and Router numbers under the TCP/IP tab of the advanced network preferences settings. Whenever I tried (and still try) to use DHCP, the automatic setting, I lose connection with the router and I get the message "Airport does not have an IP address and can not connect to the internet."
Now, I just tried the same setting, "Using DHCP" and connecting to my neighbor's wireless network and everything works just fine: I am able to access those sites which I couldn't before! Therefore, the problem arises somehow when I manually enter that stuff in in order to connect to my router and thus the internet.
Is there something else that happens automatically when "Using DHCP" that doesn't happen when I enter stuff in manually that could be causing this?
That's pretty much it. Any ideas?
Message was edited by: Wooj
Message was edited by: Wooj

Answer 1

When you get an IP address via DHCP you also receive your netmask, default router address and addresses of (in general) two DNS servers that way.
Having any of those parameters incorrect when manually setting up networking could cause the issue you're having, though the most likely suspect is an incorrect netmask.
In short, anything that is determined to be on your local LAN after application of the netmask is contacted directly; anything that is "external" is contacted via the default gateway.
Also, please don't post the same question in multiple forums; that actually reduces your chances of getting an answer as many of us will think it's already answered in a different thread.