I am looking for help with my laptop.  I am running SL 7.1 (Nitrogen) and using Mozilla Firefox 38.4.0 as my browser.  When trying to access sites on the internet I keep getting the following message:

Server not found

Firefox can't find the server at www.ScientificLinux.org.
Check the address for typing errors such as ww.example.com instead of www.example.com.
If you are unable to load any pages, check your computer's network connection.
If you computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.

I am not using a proxy and my network seems to be working fine because there are many sites that I can access.  I have looked at the network settings and cannot figure out how why they might not be correct.  I am relatively new to Linux and am not an expert by any stretch of the imagination.  This problem is frustrating me and I cannot find a solution.

Can someone out there help me?  Explain to me what my browser/network/firewall settings should be to get total access to the internet.

Thank you in advance for any help you can provide,
JB Scott