cat /etc/resolv.conf

查看是否使用静态dns

cat /etc/sysconfig/network-scripts/ifcfg-eth0

设置使用静态dns

echo "PEERDNS=no" >> /etc/sysconfig/network-scripts/ifcfg-eth0

设置dns，实时生效。

echo "nameserver 223.5.5.5" >> /etc/resolv.conf

echo "nameserver 223.6.6.6" >> /etc/resolv.conf

重启网络

/etc/init.d/network restart

如果重启网络后 resolv.conf  dns 设置自动消失，那么可以把dns添加到 ifcfg-eth0
echo "DNS1=223.5.5.5" >> /etc/sysconfig/network-scripts/ifcfg-eth0
echo "DNS2=223.6.6.6" >> /etc/sysconfig/network-scripts/ifcfg-eth0