I am attempting to setup AWS AD Connector to our on-premise Active Directory by following Amazon document "AD Connector Prerequisites".
The status is Failed with the following error.
Connectivity issues detected: DNS unavailable (TCP port 53) for IP: ..., Please ensure that the listed ports are available and retry the operation.
I am assured the port is opened as I could see that the traffics are allowed on firewall.
Below is the connectivity test from the subnet:
C:\temp\DirectoryServicePortTest>DirectoryServicePortTest.exe -d domain.local -i
p x.x.x.x -tcp "53,88,389,636" -udp "53,88,389,636"
Testing forest functional level.
Forest Functional Level = Windows2003Forest : PASSED
Testing domain functional level.
Domain Functional Level = Windows2003Domain : PASSED
Testing TCP ports to x.x.x.x:
Checking TCP port 53: PASSED
Checking TCP port 88: PASSED
Checking TCP port 389: PASSED
Checking TCP port 636: FAILED
Testing UDP ports to x.x.x.x:
Checking UDP port 53: PASSED
Checking UDP port 88: PASSED
Checking UDP port 389: PASSED
Checking UDP port 636: PASSED
Press <enter> to continue.
Any ideas about that?