cat /etc/network/interfaces

# XenSystem Ethernet
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 61.238.75.76
netmask 255.255.255.0
gateway 61.238.75.254
dns-nameservers 1.1.1.1
dns-nameservers 8.8.8.8

重启

systemd-resolve --status

Global
         DNS Servers: 1.1.1.1
                      8.8.8.8
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
            ......

不重启

sudo service systemd-resolved restart

Ubuntu 18.04 LTS 更改DNS域名服务器

原文：https://www.cnblogs.com/develon/p/10927207.html