ubuntu无法解析域名“cn.archive.ubuntu.com“，修改DNS配置_127.0.0.53 无法解析

系统：Ubuntu18.04

错误:1 http://cn.archive.ubuntu.com/ubuntu focal InRelease 无法解析域名“cn.archive.ubuntu.com"
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（1）临时解决方案

sudo vim /etc/resolv.conf

将127.0.0.53改成自己的ip（系统重启后又会变成默认值）

# This file is managed by man:systemd-resolved(8). Do not edit.
# 
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
 
nameserver 127.0.0.53
options edns0 trust-ad

（2）修改DNS，一劳永逸

sudo vim /etc/systemd/resolved.conf

取消DNS注释，添加值114.114.114.114和8.8.8.8

#  This file is part of systemd.
# 
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See resolved.conf(5) for details
 
[Resolve]
DNS= 114.114.114.114
DNS= 8.8.8.8
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#DNSOverTLS=no
#Cache=no-negative
#DNSStubListener=yes
#ReadEtcHosts=yes

重启服务，使配置生效

systemctl restart systemd-resolved 
systemctl enable systemd-resolved

ok~