Bind9 service is running on a Plesk server but does not serve DNS queries

Symptoms

• Websites hosted on a Plesk server can not be accessed in a web browser

• Domains are not resolved locally from the server:

  # dig +short example.com @localhost

• Bind9 service is running:

  # systemctl status bind9
  ● named.service - BIND Domain Name Server
  Loaded: loaded (/lib/systemd/system/named.service; enabled; vendor preset: enabled)
  Active: active (running) since Thu 2022-04-07 11:15:05 UTC; 2h 52min ago
  Docs: man:named(8)
  Process: 8835 ExecReload=/usr/sbin/rndc reload (code=exited, status=1/FAILURE)
  ...
  CGroup: /system.slice/named.service
  └─68392 /usr/sbin/named -f -u bind

  ---

  Bind9 service is in activating status:

  # service named status
  * named.service - BIND Domain Name Server
  Loaded: loaded (/lib/systemd/system/named.service; enabled; vendor preset: enabled)
  Drop-In: /lib/systemd/system/bind9.service.d
  `-respawn.conf
  Active: activating (auto-restart) (Result: exit-code) since Tue 2023-01-10 22:02:48 CST; 3s ago

• Running the following command from the server contains below output:

  # dig +trace
  (...)
  ;; BAD (HORIZONTAL) REFERRAL
  dig: too many lookups
  (...)

Cause

Incorrect options for ExecStart and EnvironmentFile in service configuration file /lib/systemd/system/named.service.

Resolution

1. Login to the server via SSH.

2. Create a backup of /lib/systemd/system/named.service

   # cp -p /lib/systemd/system/named.service /root/

3. Replace all content inside /lib/systemd/system/named.service with below:

   [Unit]
   Description=BIND Domain Name Server
   Documentation=man:named(8)
   After=network.target
   Wants=nss-lookup.target
   Before=nss-lookup.target
   [Service]
   Type=forking
   EnvironmentFile=-/etc/default/bind9
   ExecStart=/usr/sbin/named $OPTIONS
   ExecReload=/usr/sbin/rndc reload
   ExecStop=/usr/sbin/rndc stop
   [Install]
   WantedBy=multi-user.target

4. Restart bind9:

   • For Plesk on RHEL based operating systems:

     # systemctl daemon-reload
     # systemctl restart bind9.service

   • For Plesk on Debian based operating systems:

     # systemctl daemon-reload
     # systemctl restart bind9.service

5. Repair Plesk DNS:

   # plesk repair dns -y