[root@Centos ~]# yum update
Setting up Update Process
Setting up repositories
http://mirror.centos.org/centos/4/updates/i386/repodata/repomd.xml: [Errno 4] IOError: <urlopen error (-3, 'Temporary failure in name resolution')>
Trying other mirror.
Cannot open/read repomd.xml file for repository: update
failure: repodata/repomd.xml from update: [Errno 256] No more mirrors to try.
Error: failure: repodata/repomd.xml from update: [Errno 256] No more mirrors to try.