One certificate covering several different domains.
WHAT IT IS
A certificate listing multiple hostnames in its subject alternative names. They can be unrelated domains, not just subdomains.
WHEN IT IS USEFUL
One server hosting several distinct domains where you want a single certificate to manage A business with several brands on one account Reducing renewal administration across many domains
THE LIMITS
Each name must be specified at issue. Adding a name later means reissuing the certificate. Every domain must be validated. The full list of names is visible in the certificate, so unrelated businesses sharing one certificate reveal their association.
That last point matters if you host sites for different clients. A shared certificate tells each client's visitors who else you host.
AUTOSSL ALTERNATIVE
AutoSSL issues per-domain certificates automatically. Each domain is independent, nothing is revealed about the others, and nothing needs reissuing when you add a domain.
THE RECOMMENDATION
Use AutoSSL unless you have a specific reason for a single certificate.
