三个教育网的镜像服务器地址分别是：
http://ftp.sjtu.edu.cn/centos/http://mirror.lib.tsinghua.edu.cn/centos/
http://centos.ustc.edu.cn/centos/
===================================
[base]
name=CentOS-5 – Base
repo=os
baseurl=http://centos.ustc.edu.cn/centos/5.0/os/$basearch/
http://ftp.sjtu.edu.cn/centos/5.0/os/$basearch/
http://mirror.lib.tsinghua.edu.cn/centos/5.0/os/$basearch/
http://mirror.tini4u.net/centos/5.0/os/$basearch/
http://ftp.daum.net/centos/5.0/os/$basearch/
http://mirror.secuidc.com/centos/5.0/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
[update]
name=CentOS-5 – Updates
baseurl=http://centos.ustc.edu.cn/centos/5.0/updates/$basearch/
http://ftp.sjtu.edu.cn/centos/5.0/updates/$basearch/
http://mirror.lib.tsinghua.edu.cn/centos/5.0/updates/$basearch/
http://ftp.daum.net/centos/5.0/updates/$basearch/
http://mirror.secuidc.com/centos/5.0/updates/$basearch/
http://mirror.tini4u.net/centos/5.0/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
[addons]
name=CentOS-5 – Addons
baseurl=http://centos.ustc.edu.cn/centos/5.0/addons/$basearch/
http://ftp.sjtu.edu.cn/centos/5.0/addons/$basearch/
http://mirror.lib.tsinghua.edu.cn/centos/5.0/addons/$basearch/
http://ftp.daum.net/centos/5.0/addons/$basearch/
http://mirror.secuidc.com/centos/5.0/addons/$basearch/
http://mirror.tini4u.net/centos/5.0/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
[extras]
name=CentOS-5 – Extras
baseurl=http://centos.ustc.edu.cn/centos/5.0/extras/$basearch/
http://ftp.sjtu.edu.cn/centos/5.0/extras/$basearch/
http://mirror.lib.tsinghua.edu.cn/centos/5.0/extras/$basearch/
http://ftp.daum.net/centos/5.0/extras/$basearch/
http://mirror.secuidc.com/centos/5.0/extras/$basearch/
http://mirror.tini4u.net/centos/5.0/extras/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
[centosplus]
name=CentOS-5 – Plus
baseurl=http://centos.ustc.edu.cn/centos/5.0/centosplus/$basearch/
http://ftp.sjtu.edu.cn/centos/5.0/centosplus/$basearch/
http://mirror.lib.tsinghua.edu.cn/centos/5.0/centosplus/$basearch/
http://ftp.daum.net/centos/5.0/centosplus/$basearch/
http://mirror.secuidc.com/centos/5.0/centosplus/$basearch/
http://mirror.tini4u.net/centos/5.0/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
[contrib]
name=CentOS-5 – Contrib
baseurl=http://centos.ustc.edu.cn/centos/5.0/contrib/$basearch/
http://ftp.sjtu.edu.cn/centos/5.0/contrib/$basearch/
http://mirror.lib.tsinghua.edu.cn/centos/5.0/contrib/$basearch/
http://ftp.daum.net/centos/5.0/contrib/$basearch/
http://mirror.secuidc.com/centos/5.0/contrib/$basearch/
http://mirror.tini4u.net/centos/5.0/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
转自：http://louishan.com/articles/centos-cernet-yum-sources.html