Deleting a delegation from the parent zone on a primary DNS server does not increment the Start Of Authority (SOA), even if you add a record to the parent zone to force an SOA increment. You must manually delete the delegation from the DNS zone file on all secondary DNS servers.
1. Stop the DNS service on a secondary DNS server.
2. Open the zone file (example: %SystemRoot%\System32\Dns\filename.com.dns) in Notepad.
3. Delete the NS and A records for the delegation.
4. Save the zone file.
5. Start the DNS service.
NOTE: You can delete the zone file and let it transfer from the the primary DNS.
NOTE: See tip 1299.