Just thought document how we discovered the port 443 used by another application
I was trying to secure IIS on one of the server (WSUS)
Added new certificate
Added port 443 to the Website bindings
Bang… Default site stopped working…
Run netstat –ano showed PID 2720 and task manager showed PID 2720 is used by APACHE.
Another application on the server which was supposed to be decommissioned left apache running and port 443 engaged.
So I ended up in using alternate port for WSUS and issue resolved.
Anything 1024 or higher is a non-standard port and can be used. Up to 1023 have protocols in use.