YDL 5.0 update (yum and pup) fails

[C Erler]

I recently bought Yellow Dog 5.0 DVDs from Terrasoft for use on my
PS3. Attempting to update with yum (pup fails also) gives :

Cannot find a valid baseurl for repo: updates

I checked the base URL in the configuration files (which seems to be
commented out, but uncommenting doesn't help), and it seems to be
rather empty compared to the one for Yellow Dog 4.0.  How do I correct
the error I get ?