Subject Alternative Name
Additional domain names covered by this certificate
Subject Alternative Name (SAN) is an extension to X.509 certificates that allows a single SSL certificate to secure multiple domain names and IP addresses. Unlike the Common Name field which can only contain one domain, the SAN extension can include multiple DNS names, IP addresses, email addresses, and URIs. This makes SAN certificates extremely valuable for organizations that need to secure multiple domains or subdomains with a single certificate.
For example, a SAN certificate might secure www.example.com, example.com, mail.example.com, and shop.example.com all at once.
Modern browsers prioritize SAN over Common Name when validating certificates, making this extension essential for comprehensive domain coverage.
SAN certificates are also known as Multi-Domain SSL certificates and are particularly useful for consolidating certificate management and reducing costs.
Where You'll See This Term
This term commonly appears in:
- SSL certificate details pages
- Certificate Authority validation processes
- SSL configuration documentation
- Security audit reports
- Certificate management interfaces