Which of the following Ports is not required to be available for vCenter Server?

A.
443

B.
902

C.
80

D.
25

Explanation:
ESXi Installable and vCenter Server, Setup Guide, ESXi 4.0 Installable, vCenter Server
4.0, page 18.
vCenter Server requires certain ports to send and receive data.
* 80 vCenter Server requires port 80 for direct HTTP connections. Port 80 redirects
requests to HTTPS port
* 443. This is useful if you accidentally use http://server instead of https://server.
* 389 This port must be open on the local and all remote instances of vCenter Server.
This is the LDAP port number for the Directory Services for the vCenter Server group.
* 443 The default port that the vCenter Server system uses to listen for connections from
the vSphere Client.
* 636 For vCenter Linked Mode, this is the SSL port of the local instance.
* 902 The default port that the vCenter Server system uses to send data to managed hosts.
Managed hosts also send a regular heartbeat over UDP port 902 to the vCenter Server
system.