# cat /etc/resolv.conf 
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)

#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN       注意看：

1 /etc/resolv.conf 其实是一个Link

它其实指向的是 /run/resolvconf/resolv.conf 

3 如果想自己定义 nameserver，那么有以下2个办法：

A 在网卡的配置文件/etc/network/interfaces 里面加：

dns-nameservers 192.168.3.45 192.168.8.10

dns-search foo.org bar.com 

重启网络

sudo service networking restart 
或者
sudo /etc/init.d/networking restart

也可以重启网卡

sudo ifconfig eth0 down 
sudo ifconfig eth0 up

B 修改 resolvconf服务的配置文件: /etc/resolvconf/resolv.conf.d/base 

echo "search test.com" >> /etc/resolvconf/resolv.conf.d/base 

echo "nameserver 202.106.0.20 " >> /etc/resolvconf/resolv.conf.d/base 

这样，在机器重启或 resolvconf 服务重启 都可以保证配置会写到/etc/resolv.conf 里面 

重启 resolvconf 服务

service resolvconf restart

A比B的优先级更高,,不过可能会断网.