如果是国内服务器

请查看dns，是否有国外dns，有的需要删除，列如：8.8.8.8，1.1.1.1 


rm -rf /etc/yum.repos.d/CentOS-Base.repo
wget http://github.itzmx.com/1265578519/mirrors/master/CentOS/CentOS6-Base-itzmx.repo -O /etc/yum.repos.d/CentOS6-Base-itzmx.repo
rm -rf /etc/yum.repos.d/*pel.repo /etc/yum.repos.d/epel-testing.repo
wget http://github.itzmx.com/1265578519/mirrors/master/EPEL/epel.repo -O /etc/yum.repos.d/epel.repo