Plesk installation warning: Some problems are found during create reverse DNS zone

Symptoms

• The following warning was shown during Plesk Onyx installation:

  PLESK_ERROR: WARNING! Some problems are found during create reverse DNS zone – there is error during utility ‘/opt/psa/admin/sbin/mk_reverse_zone’ execution, please fix the problem and run it again.(see log file: /var/log/plesk/install/plesk_17.0.17_installation.log)

• Plesk installation may be failed with the following error:

  Trying to create reverse DNS zone: /opt/psa/admin/sbin/mk_reverse_zone[8171]:
   Canonname is not correct fqdn. 
   It is impossible to detect the FQDN of the host. 
   Please make sure that the host name is correctly specified in /etc/hosts and goes right after the host's IP Address. 
   Depending on your OS, you might need to set the host name in /etc/HOSTNAME or /etc/hostname. 
   Terminate called after throwing an instance of 'std::runtime_error' 
   what(): Error on configure reverse DNS zone for localhost : fail to detect hostname

• Server hostname is as follows:

  # hostname
  example

  Or:

  # hostname
  localhost.localdomain

Cause

Hostname of the server is not a valid FQDN name.

A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name, is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS).

Resolution

1. Connect to the server via SSH.

2. Change the server’s hostname to FQDN one:

   # hostname plesk.example.com

3. Re-run reverse DNS zone creation:

   # plesk sbin mk_reverse_zone