~ path guide

How To Read A TLS Certificate

TLS certificate checks explain whether a secure service presents a certificate that matches the hostname, has a valid date range, and chains to a trusted issuer.

Fields That Matter

• Subject Alternative Name lists the hostnames the certificate covers.
• Issuer shows who signed the certificate.
• Not Before and Not After show the valid date range.
• The hostname match decides whether the requested name is covered.

Common Problems

• Expired certificates.
• Certificate issued for a different hostname.
• Missing intermediate certificates.
• Old TLS versions or unsupported cipher suites.
• Load balancers serving the wrong certificate on one backend.

Good Troubleshooting Habit

Always check the exact hostname users enter. A certificate can be valid for www.example.com while failing for example.com, or the reverse.