XADM: Statically Mapped Port Limitations for Exchange Server

MORE INFORMATION

The system will assign ephemeral port numbers to processes as processes request them. If a process is using the statically assigned port when the Exchange Server service starts, the Exchange Server service will not be able to use that port later. The information store and the directory service will still register all of its other endpoints, and start successfully.

If static entries are needed for the customer's configuration, Microsoft recommends that you follow these guidelines:

• Select ports just above 5000.
  
  -or-
• Select a port number in the 4900 - 5000 range. Programs almost never use the ports at this high end of the ephemeral range because ports are typically taken from the low end of the range first.
  
  -or-
• Select ports just below 1024.
  
  NOTE: The issue is with the use of "well-known ports." To make sure the port selected below port 1024 is not in conflict with another process, see Request for Comment (RFC) 1060.

Mapping to ports from the low end of the ephemeral range is possible, but programs that use ephemeral ports choose them at random, typically starting at the low end of the range, and may conflict with the ports that you have manually assigned Exchange to use.