ubuntu18.04更改dns server

打开 /etc/systemd/resolved.conf，设置变量DNS:

$ sudo gedit  /etc/systemd/resolved.conf

2. 单击"save" 按钮，保存设置

3. 输入一下命令，使设置生效

$ systemctl restart systemd-resolved //重启systemd-resolved服务
$ systemctl enable systemd-resolved//使能systemd-resolved服务

$ mv /etc/resolv.conf  /etc/resolv.conf.bak//备份修改前的resolv.conf，这一步可以省略。
$ ln -s /run/systemd/resolve/resolv.conf /etc/  //这一步必须执行，否则DNS设置不能有效