-bash-3.00# yum search header
Searching Packages: 
Setting up repositories
//var/cache/yum/dag/repomd.xml:1: parser error : Document is empty

^
//var/cache/yum/dag/repomd.xml:1: parser error : Start tag expected, '<' not found

^
dag                       100% |=========================|    0 B    00:00     
http://apt.sw.be/redhat/el4/en/i386/dag/repodata/repomd.xml: [Errno -1] Error importing repomd.xml for dag: Error: could not parse file //var/cache/yum/dag/repomd.xml
Trying other mirror.
Cannot open/read repomd.xml file for repository: dag
failure: repodata/repomd.xml from dag: [Errno 256] No more mirrors to try.
Error: failure: repodata/repomd.xml from dag: [Errno 256] No more mirrors to try.
-bash-3.00#