各位好，我在Debian 11服务器上运行apt-get update命令时遇到了域名解析失败的问题，导致所有软件源都无法正常获取更新信息。完整的命令输出如下：

Err:1 http://deb.debian.org/debian bullseye InRelease
  Temporary failure resolving 'deb.debian.org'
Err:2 http://packages.sury.org/php bullseye InRelease
  Temporary failure resolving 'packages.sury.org'
Err:3 http://deb.debian.org/debian bullseye-updates InRelease
  Temporary failure resolving 'deb.debian.org'
Err:4 http://security.debian.org/debian-security bullseye-security InRelease
  Temporary failure resolving 'security.debian.org'
Err:5 htttp://deb.nodesource.com/node_14.x bullseye InRelease
  Temporary failure resolving 'deb.nodesource.com'
Err:6 http://repo.mysql.com/apt/debian buster InRelease
  Temporary failure resolving 'repo.mysql.com'
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.

W: Failed to fetch http://deb.debian.org/debian/dists/bullseye/InRelease  Temporary failure resolving 'deb.debian.org'
W: Failed to fetch http://security.debian.org/debian-security/dists/bullseye-security/InRelease  Temporary failure resolving 'security.debian.org'
W: Failed to fetch http://deb.debian.org/debian/dists/bullseye-updates/InRelease  Temporary failure resolving 'deb.debian.org'
W: Failed to fetch http://packages.sury.org/php/dists/bullseye/InRelease  Temporary failure resolving 'packages.sury.org'
W: Failed to fetch htttp://deb.nodesource.com/node_14.x/dists/bullseye/InRelease  Temporary failure resolving 'deb.nodesource.com'
W: Failed to fetch http://repo.mysql.com/apt/debian/dists/buster/InRelease  Temporary failure resolving 'repo.mysql.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.

目前我确认服务器能正常连接外网，但就是无法解析这些软件源的域名，有没有大佬能指点一下排查和解决的方法呀？

备注：内容来源于stack exchange，提问作者tlholoheloh101