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Subject Alternative Name (SAN) is an extension to X.509 that allows various values to be associated with a security certificate using a subjectAltName field.[1] These values are called Subject Alternative Names (SANs). Names include:[2]
- Email addresses
- IP addresses
- URIs
- DNS names: this is usually also provided as the Common Name RDN within the Subject field of the main certificate.
- Directory names: alternative Distinguished Names to that given in the Subject.
- Other names, given as a General Name or Universal Principal Name: a registered object identifier followed by a value.
RFC 2818 (May 2000) specifies Subject Alternative Names as the preferred method of adding DNS names to certificates, deprecating the previous method of putting DNS names in the commonName field.[3] Google Chrome version 58 (March 2017) removed support for checking the commonName field at all, instead only looking at the SANs.[3]