Iam having the same issue on a system I installed and want to chime in with some info.
I used the fedora 11 cd for x86-64 for install. Same disk as my home system that gets its connection from comcast and I have no problems what so ever. I did an update (yum -y update) and rebooted and still no issues. Everything runs fine on my home system.
Now, On system2 I built using gigabyte MB/AMD dual core at another location also in comcast I had the same outcome. No problems what so ever. Just like my home system.
Then--- I installed an exact same system as system2 but gets its connection from AT&T DSL (yahoo, Ill call it system3). System3 is connected to a motorola dsl box (model 2210-02) and I did NOT do any updating. What I found was I can surf the net ok with firefox but I cannot do any yum updates. Yum errors out with the mentioned error message. I have tried to add fedora to the hosts file and doing a yum update but I get alot of errors for sites being busy. So, Its not really a fix.
/etc/nsswitch.conf file contains the line: hosts: files dns
This is the same line that is in the nsswitch.conf file of the other boxes that work fine.
Therefore, I think its something related to how a DSL connection (pppoe ? ) is handled as any boxes connected to something else like comcast have no problem. As far as I can figure the dsl modem handles pppoe internally so there is no reason that would be a problem.
In reading the above posts I didnt see any mention of what type of connection the boxes where on that are having this issue. Might it be a DSL connection issue within fedora??
Love to hear from anyone with their point of view on this and any real fixes possible.