The easiest option is to let DNS Manager act as a slave DNS server for your multiple Plesk servers, which have DNS Zones set as primary.

For this to be possible, the following requirements need to be met:

1. DNS Manager is allowed to obtain DNS Zone information from the primary server.

2. DNS Manager knows the names of the DNS Zones which must obtained from the primary server.

Step-by-step guide

Getting DNS Zone information from the primary server

1. Configure the DNS server on the Plesk server so that it allows transfer from the DNS Manager IP.
2. Since every DNS Zone created on a Plesk server includes an ACL called common-allow-transfer, you need to include the IP of the DNS Manager in the Global Transfer IPs page. Or you can add the Allow transfer IPs in the Remote Update Locations page.

3. Since Plesk uses its database to write the named.conf file, the best solution is to insert the IP address of the DNS Manager server in the psa database. This way you can be sure that the named.conf file will remain correct. To do this, execute the following commands in the psa database:

   MySQL>INSERT INTO misc VALUES ('DNS_Allow_TransferXX','<Secondary Server IP>');

   Where:

   XX is a unique number (increment it to add more IP addresses) and <Secondary Server IP> is the IP of the DNS Manager server.

Getting DNS Zones information from the master server

1. In order to do this we will install on the Plesk server a script shipped with DNS Manager, which is located in DNSMANAGER_ROOT_D/remote directory. The plesk_export.sh is a shell script written by 4PSA for Plesk servers, which writes a file with the names of all the domains existing on that server. The script accepts the final destination file as argument. 
2. Insert the file in cron and make sure that it will write the list of the domains to a directory which can be accessed over the web.

3. Configure the script to export slaves zones and master records (edit the script to set the required variables as defined in the script). For example, the command below will dump the list of domains to a file that can be accessed at http://www.mydomain.com/dnslist.txt

   sh plesk_export.sh /home/httpd/vhosts/mydomain.com/httpdocs/dnslist.txt

   
   

   Keep in mind that you must add the plesk_export.sh invocation in cron on the Plesk server. This way the dnslist.txt file will be updated at regular time intervals and DNS Manager will retrieve the latest list of the domains available on the server.

   
   

4. Set up DNS Manager to update the list of the DNS Zones from this location. This will be a remote update location in DNS Manager. 

 For more information on how to set up remote update locations, view the Managing remote update locations section.