yum 업데이트 저장소를 변경 하는 방법입니다.
CentOS-Base.repo 파일을 편집합니다.

[root@ruo91 ~]# nano /etc/yum.repos.d/CentOS-Base.repo

CentOS-Base.repo 에 mirrorlist 주석 체크 후 baseurl 안에 원하는 서버주소를 써주시면 됩니다.

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
[base]
name=CentOS-$releasever – Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
baseurl=http://mirror.yongbok.net/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.yongbok.net/centos/RPM-GPG-KEY-CentOS-5
#released updates
[updates]
name=CentOS-$releasever – Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
baseurl=http://mirror.yongbok.net/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.yongbok.net/centos/RPM-GPG-KEY-CentOS-5

#packages used/produced in the build but not released
[addons]
name=CentOS-$releasever – Addons
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
baseurl=http://mirror.yongbok.net/centos/$releasever/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.yongbok.net/centos/RPM-GPG-KEY-CentOS-5

#additional packages that may be useful
[extras]
name=CentOS-$releasever – Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
baseurl=http://mirror.yongbok.net/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirror.yongbok.net/centos/RPM-GPG-KEY-CentOS-5

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever – Plus
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
baseurl=http://mirror.yongbok.net/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.yongbok.net/centos/RPM-GPG-KEY-CentOS-5

#contrib – packages by Centos Users
[contrib]
name=CentOS-$releasever – Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
baseurl=http://mirror.yongbok.net/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.yongbok.net/centos/RPM-GPG-KEY-CentOS-5