Currently we need to deploy a new on premises Exchange 2019 with 500 mailboxes, This exchange server will work as an internal only exchange server.
At the same time we have Exchange Online with 60 mailboxes. The current Domain name used for the Exchange online is (For example) MYDOMAIN.COM and The current on premises AD domain name is CORP.MYDOMAIN.COM
The Question is: what is the best practice for the name spacing for the on premises exchange server when it comes to DNS configuration
should we go to a hybrid solution, we thought about it but we decided not to because the number of users needs to go online is so few in comparison to the major number of the employees
