CentOS yum时出现“Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=5&arch=i386&repo=addons error ”错误：
[root@server mysql-5.0.56]# yum install gcc
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=5&arch=i386&repo=addons error was
[Errno 4] IOError: <urlopen error (-3, '\xe5\x9f\x9f\xe5\x90\x8d\xe8\xa7\xa3\xe6\x9e\x90\xe6\x9a\x82\xe6\x97\xb6\xe5\xa4\xb1\xe8\xb4\xa5')>
Error: Cannot find a valid baseurl for repo: addons
发现原来是没有配置resolv.conf，于是到/etc目录下配置resolv.conf加入nameserver IP：
[root@server mysql-5.0.56]# vi /etc/resolv.conf
nameserver 218.85.157.99
search localdomain
保存resolv.conf，再次运行上面命令就可以。
[root@server mysql-5.0.56]# yum install gcc
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.ustc.edu.cn
* extras: centos.ustc.edu.cn
* updates: centos.ustc.edu.cn
addons | 951 B 00:00
addons/primary | 202 B 00:00
base | 1.1 kB 00:00
base/primary | 961 kB 00:06
base 2705/2705
extras | 2.1 kB 00:00
extras/primary_db | 171 kB 00:00
updates | 1.9 kB 00:00
..........................................................................................
.................................................................................
................................................................