Full (strict) - SSL/TLS encryption modes
When you set your encryption mode to Full (strict), Cloudflare does everything in Full mode but also enforces more stringent requirements for origin certificates.
Use when
For the best security, choose Full (strict) mode whenever possible (unless you are an Enterprise customer).
Your origin needs to be able to support an SSL certificate that is:
- Unexpired, meaning the certificate presents
notBeforeDate < now() < notAfterDate. - Issued by a publicly trusted certificate authority or Cloudflare’s Origin CA.
- Contains a Common Name (CN) or Subject Alternative Name (SAN) that matches the requested or target hostname.
Required setup
Before enabling Full (strict) mode, make sure your origin allows HTTPS connections on port 443 and presents a certificate matching the requirements above. Otherwise, your visitors may experience a 526 error.
Limitations
Depending on your origin configuration, you may have to adjust settings to avoid Mixed Content errors or redirect loops.