sudo vi /etc/systemd/resolved.conf

然后修改DNS，例如：

[Resolve]
DNS=114.114.114.114
DNS=8.8.8.8
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#Cache=yes
#DNSStubListener=yes

然后

systemctl restart systemd-resolved.service

查看结果：

$ systemd-resolve --status
Global
DNS Servers: 114.114.114.114
8.8.8.8
DNSSEC NTA: 10.in-addr.arpa
16.172.in-addr.arpa
168.192.in-addr.arpa
17.172.in-addr.arpa
18.172.in-addr.arpa
19.172.in-addr.arpa