システム構成

OS
- Ubuntu 20.04 LTS
Samba Version
- 4.11.6-Ubuntu

エラー内容

$ sudo systemctl status samba-ad-dc.service
* samba-ad-dc.service - Samba AD Daemon
     Loaded: loaded (/lib/systemd/system/samba-ad-dc.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Sat 2021-07-24 23:47:41 JST; 29s ago
       Docs: man:samba(8)
             man:samba(7)
             man:smb.conf(5)
    Process: 3200 ExecStart=/usr/sbin/samba --foreground --no-process-group $SAMBAOPTIONS (code=exited, status=1/FAILURE)
   Main PID: 3200 (code=exited, status=1/FAILURE)
     Status: "Starting process..."

Jul 24 23:47:41 ik1-442-53089 samba[3212]:   task_server_terminate: task_server_terminate: [smbd child process exited]
Jul 24 23:47:41 ik1-442-53089 samba[3200]: [2021/07/24 23:47:41.712654,  0] ../../source4/smbd/server.c:370(samba_terminate)
Jul 24 23:47:41 ik1-442-53089 samba[3200]:   samba_terminate: samba_terminate of samba 3200: smbd child process exited
Jul 24 23:47:41 ik1-442-53089 systemd[1]: samba-ad-dc.service: Main process exited, code=exited, status=1/FAILURE
Jul 24 23:47:41 ik1-442-53089 samba[3256]: [2021/07/24 23:47:41.781743,  0] ../../source4/smbd/service_stream.c:372(stream_setup_socket)
Jul 24 23:47:41 ik1-442-53089 samba[3256]:   stream_setup_socket: Failed to listen on 0.0.0.0:53 - NT_STATUS_ADDRESS_ALREADY_ASSOCIATED
Jul 24 23:47:41 ik1-442-53089 samba[3256]: [2021/07/24 23:47:41.781858,  0] ../../source4/dns_server/dns_server.c:648(dns_add_socket)
Jul 24 23:47:41 ik1-442-53089 samba[3256]:   Failed to bind to 0.0.0.0:53 TCP - NT_STATUS_ADDRESS_ALREADY_ASSOCIATED
Jul 24 23:47:41 ik1-442-53089 systemd[1]: samba-ad-dc.service: Failed with result 'exit-code'.
Jul 24 23:47:41 ik1-442-53089 systemd[1]: Failed to start Samba AD Daemon.

治し方

ポート53を使用中のソフトを特定する

$ sudo lsof -i:53

特定したソフトを停止

$ sudo systemctl stop [ソフト名]
$ sudo systemctl disable [ソフト名]

例は参考にしたサイトがわかりやすいと思います！↓
参考にしたサイト→　https://www.ytyng.com/blog/ubuntu-samba-ad-dc-dns/