# cd /etc/yum.repos.d/
# mv CentOS-Base.repo CentOS-Base.repo.bak
# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
# mv CentOS6-Base-163.repo CentOS-Base.repo
# yum clean all
# yum makecache
# yum update # cd /etc/yum.repos.d/
# mv CentOS-Base.repo CentOS-Base.repo.bak
# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
# mv CentOS6-Base-163.repo CentOS-Base.repo
# yum clean all
# yum makecache
# yum update