When it is safe to remove DNS Server (Active Directory Integrated)
Not necessarily all points only No. 2 applies to Primary Server.
I have posted basic guidelines for removing DNS server from the network.
Here is a list of points for your review:
You can safely remove any DNS server running in your network BUT you should not if the following conditions are true:
1. If this DNS server is authoritative for a Active Directory domain or DNS Domain Zone.
If you remove any DNS server that is authoritative for any domain zone configured in your network. It will remove the SRV records from zone and connectivity to domain controllers through DNS server.
2. If this is the primary DNS Server and you have configured rest of DNS servers on other DCs to work as secondary DNS Servers then you should not remove this DNS server. Doing so will cause replication failures. Secondary servers will be inoperable.
3. If any domain is delegated under this DNS server.
4. If this DNS server contains the SOA records for other authoritative DNS Server for zone.
5. Your clients are configured to use this DNS server. Removing this DNS server from operation will cause problems,
clients won't be able to log on to network or find domain controllers.
The above are the basic guidelines to consider while removing a DNS server from your network.