Important ports and their purposes

Ports:

TCP: 53, 135, 389, 445 ,464, 636, 3268, 3269, 49152–65535
UDP: 53, 88, 135, 389, 445, 464, 636, 3268, 3269, 123, 137, 138

Purpose of the ports:

• UDP Port 88 for Kerberos authentication
• UDP and TCP Port 135 for domain controllers-to-domain controller and client to domain controller operations.
• TCP Port 139 and UDP 138 for File Replication Service between domain controllers.
• TCP and UDP Port 389 for LDAP to handle normal queries from client computers to the domain controllers.
• TCP and UDP Port 445 for File Replication Service
• TCP and UDP Port 464 for Kerberos Password Change
• TCP Port 3268 and 3269 for Global Catalog from client to domain controller.
• TCP and UDP Port 53 for DNS from client to domain controller and domain controller to domain controller.
• UDP Port 123: NTP
• UDP Port 137: NetBIOS Name Resolution
• TCP Port 49152–65535: Random Port for RPC

Reference:

https://docs.microsoft.com/en-us/troubleshoot/windows-server/networking/service-overview-and-network-port-requirements#4