When synchronizing data between two Active Directory domains, Synchronization Service uses the following ports to access domain controllers in the domains:
Port |
Protocol |
Type of traffic |
Direction of traffic |
53 |
TCP/UDP |
DNS |
Inbound |
88 |
TCP/UDP |
Kerberos |
Outbound |
389 |
TCP/UDP |
LDAP |
Outbound |
636 |
TCP |
LDAP over SSL (LDAPS) |
Outbound |