I am getting the following error:

# yum update
Setting up Update Process
Setting up repositories
http://apt.sw.be/fedora/4/en/i386/da...ta/repomd.xml: [Errno 4] IOError: HTTP Error 404: Date: Mon, 05 Jun 2006 10:42:12 GMT
Server: Apache/2.2.2 (Unix)
Content-Length: 310
Content-Type: text/html; charset=iso-8859-1
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.

I have found several copies of that file:

file:///var/cache/yum/base/repomd.xml
file:///var/cache/yum/core/repomd.xml
file:///var/cache/yum/dag/repomd.xml
file:///var/cache/yum/dries/repomd.xml
file:///var/cache/yum/extras/repomd.xml
file:///var/cache/yum/freshrpms/repomd.xml
file:///var/cache/yum/livna/repomd.xml
file:///var/cache/yum/updates/repomd.xml
file:///var/cache/yum/updates-released/repomd.xml

What am I missing for yum to work for updates?

A 404 error means it cant be found, maybe dag has moved/taken off line it's FC4 repo?, the other bits usually happen when it cant reach any mirrors.

Depending on how you have set the repos, in /etc/yum/repos.d/ or in /etc/yum.conf (places may vary its bee na while) you can set enabled=0 in the dag one to skip oer it and still use the others.

check the thread

http://www.linuxquestions.org/questi...d.php?t=459931

maybe this will help