DigiCert Subject Alternative Name (SAN) Certificates can secure multiple fully qualified domain names with a single certificate. SAN Certificates are often needed to secure Exchange Server or Office Communications Server and in instances where you need to secure multiple domains that resolve to a single IP address (such as in a shared hosting environment).
SAN Certificates allow you to secure a primary domain and then add additional domains to the Subject Alternative Name field of the certificate. For example, you can secure all these domains with a single SAN Certificate:
SAN is an optional feature available for Secure Site Pro with EV, Secure Site with EV, Secure Site Pro, Secure Site Wildcard, and Secure Site Certificates.