BIND DNS Server failed

● named.service - Berkeley Internet Name Domain (DNS)
   Loaded: loaded (/usr/lib/systemd/system/named.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sat 2018-10-27 13:34:44 UTC; 22min ago
  Process: 837 ExecStartPre=/bin/bash -c if [ ! "$DISABLE_ZONE_CHECKING" == "yes" ]; then /usr/sbin/named-checkconf -z "$NAMEDCONF"; else echo "Checking of zone files is disabled"; fi (code=exited, status=1/FAILURE)

Oct 27 13:34:44 panel.blackfox.com.bd systemd[1]: Starting Berkeley Internet Name Domain (DNS)...
Oct 27 13:34:44 panel.blackfox.com.bd bash[837]: /etc/named.conf:62: zone 'ns1.blackfox.com.bd': already exists previous definition: /etc/named.conf:61
Oct 27 13:34:44 panel.blackfox.com.bd systemd[1]: named.service: control process exited, code=exited status=1
Oct 27 13:34:44 panel.blackfox.com.bd systemd[1]: Failed to start Berkeley Internet Name Domain (DNS).
Oct 27 13:34:44 panel.blackfox.com.bd systemd[1]: Unit named.service entered failed state.
Oct 27 13:34:44 panel.blackfox.com.bd systemd[1]: named.service failed.

It seems that there is a duplicate DNS entry of ns1.blackfox.com.bd in /etc/named.conf

Login to SSH and and edit this file /etc/named.conf and delete the entry ns1.blackfox.com.bd