What is the term used for a field in a digital certificate that allows identification by multiple host names?

The correct term for a field in a digital certificate that allows identification by multiple host names is the Subject Alternative Name (SAN). This field is crucial in the context of certificates, particularly for securing websites and services that may be accessed under different domain names or subdomains.

The Subject Alternative Name field extends the capabilities of a digital certificate beyond the primary domain specified in the Common Name (CN) field. By listing additional domain names, subdomains, or IP addresses within the SAN, a single certificate can validate multiple identifiers. This is especially useful for environments where multiple services might be hosted on the same IP address or when a website has multiple domain names that should all be secured under a single SSL/TLS certificate.

Choosing the Subject Alternative Name instead of other options like the hostname field, which typically refers only to the primary domain, or multi-domain name or certificate field, which are not standard terminologies recognized in certificate specifications, reinforces why SAN is the critical terminology for this function.