ubuntu解决域名不能访问的问题

刚装好的ubuntu22.04或ubuntu20.04不能访问百度，然后发现只能ping通ip，而不能ping通www.baidu.com，网上查了下解决方案，

方案一：修改dns：
修改 /etc/resolv.conf配置文件，但很快就会被覆盖，文件第二行已经声明Do not edit.

# 显示如下
# This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# 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 should typically 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
nameserver 8.8.8.8
nameserver 114.114.114.114
options edns0 trust-ad
search .

将nameserver改为8.8.8.8后保存，再次ping www.baidu.com恢复正常，不出意外的话很快就会发现/etc/resolve.conf又回去了，只好再次寻找查找解决办法

方案二：
修改/etc/systemd/resolved.conf，去除DNS前的#，修改值如下：

#  This file is part of systemd.
  2 #
  3 #  systemd is free software; you can redistribute it and/or modify it under the
  4 #  terms of the GNU Lesser General Public License as published by the Free
  5 #  Software Foundation; either version 2.1 of the License, or (at your option)
  6 #  any later version.
  7 #
  8 # Entries in this file show the compile time defaults. Local configuration
  9 # should be created by either modifying this file, or by creating "drop-ins" in
 10 # the resolved.conf.d/ subdirectory. The latter is generally recommended.
 11 # Defaults can be restored by simply deleting this file and all drop-ins.
 12 #
 13 # Use 'systemd-analyze cat-config systemd/resolved.conf' to display the full config.
 14 #
 15 # See resolved.conf(5) for details.
 16 
 17 [Resolve]
 18 # Some examples of DNS servers which may be used for DNS= and FallbackDNS=:
 19 # Cloudflare: 1.1.1.1#cloudflare-dns.com 1.0.0.1#cloudflare-dns.com 2606:4700:4700::    1111#cloudflare-dns.com 2606:4700:4700::1001#cloudflare-dns.com
 20 # Google:     8.8.8.8#dns.google 8.8.4.4#dns.google 2001:4860:4860::8888#dns.google     2001:4860:4860::8844#dns.google
 21 # Quad9:      9.9.9.9#dns.quad9.net 149.112.112.112#dns.quad9.net 2620:fe::fe#dns.qu    ad9.net 2620:fe::9#dns.quad9.net
 22 DNS=8.8.8.8 114.114.114.114
 23 #FallbackDNS=
 24 #Domains=
 25 #DNSSEC=no
 26 #DNSOverTLS=no
 27 #MulticastDNS=no
 28 #LLMNR=no
 29 #Cache=no-negative
 30 #CacheFromLocalhost=no
 31 #DNSStubListener=yes
 32 #DNSStubListenerExtra=
 33 #ReadEtcHosts=yes
 34 #ResolveUnicastSingleLabel=no

重启域名解析服务

systemctl restart systemd-resolved
systemctl enable systemd-resolved

备份当前的/etc/resolve.conf，并重新设置/run/systemd/resolve/resolv.conf 到/etc/resolve.conf的软链接

mv /etc/resolv.conf /etc/resolv.conf.bak
ln -s /run/systemd/resolve/resolv.conf /etc/

大功告成

ubuntu解决域名不能访问的问题

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