Questo qua è il log:

[root@localhost ~]# yum update
Setting up Update Process
Setting up Repo: at-stable
repomd.xml 100% |=========================| 951 B 00:00
Setting up Repo: base
repomd.xml 100% |=========================| 1.1 kB 00:00
Setting up Repo: updates-released
Cannot open/read repomd.xml file for repository: updates-released
failure: repodata/repomd.xml from updates-released: [Errno 256] No more mirrorsto try.