Multi-domain TLS/SSL certificates by Buypass AS are designed to secure multiple main domains and subdomains with a single SSL certificate. This type of certificate is typically used in environments such as Skype for Business, Lync, and Exchange, where there is a need to consolidate multiple main domains and subdomains into the same SSL certificate. These certificates are often referred to as SAN (Subject Alternative Name) or UC (Unified Communications) certificates. They offer a flexible solution that can secure an unlimited number of domains, making them ideal for organizations with complex domain structures.