Common Name (CN) is a traditional certificate subject field that historically identified the primary name associated with a certificate. It matters because certificate operators still encounter CN constantly even though modern validation practices often rely more heavily on SANs.
What is Common Name (CN)?
The common name may represent a hostname, person, or organization depending on certificate type and era. In modern web PKI, SAN handling is usually more important for hostname validation, but CN remains a familiar field in certificate tooling and legacy contexts.
What Common Name (CN) Commonly Supports
Common uses include certificate inspection, legacy certificate conventions, identity display, and historical PKI compatibility.
Common Name (CN) vs. Subject Alternative Name (SAN)
CN is a traditional single field in the subject. SAN provides a more flexible and explicit way to list one or more valid identities.
Frequently Asked Questions
Why do people still mention CN so often?
Because it has been part of certificate practice for a long time and still appears in many tools and legacy discussions.
Is CN enough for modern hostname validation?
Usually no. Modern validation commonly depends on SAN fields instead.
