You have an Exchange Server 2013 organization that contains the servers configured as shown in the following table.
All inbound messages from the Internet are received by EX1 and EX2.
You notice several communication errors between Subnet1 and Subnet2. Another administrator is working to resolve the communication errors.
You need to identify if email delivery to the organization fails due to the communication errors by monitoring the inbound TCP ports in Subnet2.
Which port should you monitor?
A. 25
B. 475
C. 587
D. 2525
