说明：
centos默认的yum更新源为mirrorlist.centos.org，由于身处国外，速度较慢，因此将yum更新源设置为163.
国内提供yum更新源的，有很多，如清华，中科大，搜狐等。这里，我选择的是163
实现：
1.获取CentOS_Base.repo配置文件
# cd /etc/yum.repos.d/ # mv CentOS-Base.repo CentOS-Base.repo.bak //备份原始配置文件 # wget http://dl.gaingreat.com/CentOS6-Base-163.repo //获取CentOS 6.*的repo，注意将CentOS6-Base-163.repo所有的$releasever改为6！！！也可以复制附录2内容到CentOS_Base.repo。CentOS 5.*为http://dl.gaingreat.com/CentOS5-Base-163.repo
2.删除缓存,重新更新
# yum clean all # yum makecache //也可以yum-plugin-fastestmirror(自动添加高速源,自动挑选快的镜像站,未试) # yum install yum-fastestmirror 注:确定/etc/yum.conf中的plugins=1
附录：
附录1：yum update出现关于addons相关问题。因为centos 6.*已经将[addons]已经替换为[centosplus]，所以需要将[addons]那段注释或删掉。centos 5.*不需要更改。具体可以到http://mirrors.163.com/centos查看下面有哪些目录。
附录2：# cat CentOS-Base.repo //CentOS 6.*内容，注意将CentOS6-Base-163.repo所有的$releasever改为6！！！
# 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-$releasever - Base - 163.com baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6 #released updates [updates] name=CentOS-$releasever - Updates - 163.com baseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6 #additional packages that may be useful [extras] name=CentOS-$releasever - Extras - 163.com baseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus - 163.com baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus gpgcheck=1 enabled=0 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6 #contrib - packages by Centos Users [contrib] name=CentOS-$releasever - Contrib - 163.com baseurl=http://mirrors.163.com/centos/$releasever/contrib/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib gpgcheck=1 enabled=0 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
附录3：CentOS [Errno 14] PYCURL ERROR 6 – ＂＂
使用CentOS 6的过程中遇到的些问题，有些其实与版本无关，是系统管理方面的问题，比如yum update 时，出现了大量的 [Errno 14] PYCURL ERROR 6 – “” 错误。
有可能是因为系统nameserver没有配置好或者说DNS解析有问题，网络有问题也是有可能的
修改/etc/resolv.conf，原来的配置为
# Generated by NetworkManager search 202.96.209.6 nameserver 202.96.209.6
可能202.96.209.6这个DNS服务器已经不能正常工作，修改后的配置
# Generated by NetworkManager #search 202.96.209.133 nameserver 8.8.8.8 nameserver 8.8.4.4 nameserver 202.96.209.6