系统不能升级

系统不能升级，点击“列出可升级”后，下面是日志。有懂的帮帮忙 谢谢，
Process 2295 (yum) has been started.
Please be patient, this may be a lengthy operation...

(Command being executed: yum -y info updates).

Loading "installonlyn" plugin
*** http://www.redflag-linux.com/source/yum/dt60sp1/Update/RPMS/repodata/dist.dat: [Errno 4] IOError: HTTP Error 404: Date: Tue, 23 Dec 2008 05:07:33 GMT
*** Server: Apache/2.0.46 (Asianux)
*** Content-Length: 336
*** Connection: close
*** Content-Type: text/html; charset=iso-8859-1
***
*** Trying other mirror.
*** http://www.redflag-linux.com/source/yum/dt60sp1/Update/RPMS/repodata/repomd.xml: [Errno 4] IOError: HTTP Error 404: Date: Tue, 23 Dec 2008 05:07:33 GMT
*** Server: Apache/2.0.46 (Asianux)
*** Content-Length: 338
*** Connection: close
*** Content-Type: text/html; charset=iso-8859-1
***
*** Trying other mirror.
*** Error: Cannot retrieve repository metadata (repomd.xml) for repository: %s. Please verify its path and try again
Try to update /etc/sysconfig/dist.dat
Retrieve the dist.dat failed, still to continue
Process exited normally with code 1.