Problems with Yum attempting to reach non-redhat mirror

I am experiencing an issue with one of our several RedHat servers getting Yum updates.  A few weeks ago, Yum updates have been failing due to the fact that the server is asking a non-redhat (no in their IP block) device for updates.  I see that the https session is being dropped by our firewall egress rules which is what I would expect because it is going after a different server than all the rest of my servers.  The message I receive is...

------<snip>-----
[root@xxxyyyzzz ~]# yum update
Loading "security" plugin
Loading "rhnplugin" plugin
Could not retrieve mirrorlist http://apt.sw.be/redhat/el5/en/mirrors-rpmforge error was
[Errno 4] IOError: <urlopen error (110, 'Connection timed out')>
Error: Cannot retrieve repository metadata (repomd.xml) for repository: rpmforge. Please verify its path and try again
-----<end snip>-----

I cannot find anywhere how yum is configured to go after one mirror server or another.  Can anyone help on this?

Cheers,

JDP