The extension also migrates the DNS entries. I did it once and the public slaves had multiple masters, all Plesk servers.
For the record I just tried this on a domain on 18.0.52. The Plesk migrator extension does migrate DNS. It does create an AAAA record for ipv4.domain and an A record for ipv6.domain. It tries to "addzone" the domain and doesn't say it fails but then immediately rejects the transfer:
May 19 10:11:21 ns1 named[17931]: received control channel command 'addzone example.com IN { type slave; file "example.com"; masters { 74.x.x.x; }; };'
May 19 10:11:21 ns1 named[17931]: received control channel command 'refresh example.com IN '
May 19 10:12:28 ns1 named[17931]: received control channel command 'refresh example.com IN '
May 19 10:12:28 ns1 named[17931]: received control channel command 'refresh example.com IN '
May 19 10:12:30 ns1 named[17931]: received control channel command 'refresh example.com IN '
May 19 10:12:31 ns1 named[17931]: received control channel command 'refresh example.com IN '
May 19 10:12:36 ns1 named[17931]: client @0x7f0d8c106000 74.x.x.x#22124: received notify for zone 'example.com'
May 19 10:12:36 ns1 named[17931]: zone example.com/IN: refused notify from non-master: 74.x.x.x#22124
If I delete the account off the old server, I can make a DNS change on the new server and update it, and then it pushes the zone to the slaves correctly. I did not try to Disable DNS on the source, that might work without deleting everything.
As a side note it seems like the DNS Slave extension should also add IPv6 addresses as masters because the NSs reject IPv6 notify commands. Which the master is using despite me having specified an IPv4 as the master and slave IPs. Probably because it's resolving the NS hostname and using that?