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    TroubleshootingBeginner

    Subject Alternative Names (SAN)

    Master SANs for multi-domain certificates. See SAN types: DNS, IP, email, and URI with real examples.

    Interactive Demo
    LinkedInX
    SAN Explainer

    Does Your Domain Match?

    Enter a domain to test against certificate SANs

    Match Found!

    "www.shop.example.com" matches at least one SAN entry in this certificate.

    Certificate SANs

    DNS:example.com
    DNS:www.example.com
    DNS:*.example.com
    DNS:api.example.com
    DNS:*.shop.example.com

    Match Results

    DNS:example.com
    No match
    DNS:www.example.com
    No match
    DNS:*.example.com
    Wildcard only matches one level (found: www.shop)
    DNS:api.example.com
    No match
    DNS:*.shop.example.com
    Wildcard matches "www" level

    Key Rule

    Wildcards (*.example.com) only match ONE subdomain level. They don't match the bare domain or multi-level subdomains.