SAN Certificates or UC SSL Certificates provide significant cost savings by securing up to 25-250 Multi-Application or UC Environments/domains with a single SSL certificate. This can simplify situations that would require multiple IP addresses because one IP address per certificate is normally required.
The defining feature of a UC SSL Certificate is the use of the SAN field in the certificate and any number of different domain names or common names (up to 250 for Entrust Wildcard ONLY).