A DNS SAN (Subject Alternative Name) is an extension of the X.509 certificate standard that allows specifying additional hostnames or IP addresses that the certificate can be used for. A DNS SAN is useful for validating the identity of the server or client that presents the certificate, especially when the common name (CN) field does not match the hostname or IP address of the server or client.

In this case, the certificate has a CN of mc41.site94.example.com, which is the fully qualified domain name (FQDN) of the standalone Aruba Mobility Controller (MC). However, this CN may not match the hostname or IP address that the MC uses for the Web UI or for implementing RadSec with Aruba ClearPass Policy Manager. For example, if the MC uses a different FQDN, such as mc41.example.com, or an IP address, such as 192.168.1.41, for these purposes, then the certificate would not be valid for them. Therefore, the certificate should have a DNS SAN that includes all the possible hostnames or IP addresses that the MC may use for the Web UI and RadSec.