Orange Book
Fundamentals

TLS modes and two encrypted legs

Choose Flexible, Full, or Full strict by separating visitor-to-edge and edge-to-origin connections.

Edited and verified by Orange Book Editorial Team ·

FUNDAMENTALBEGINNER14 minutesVerified 2026-08-26

Secure default

Prepare a valid origin certificate and prefer Full (strict). Flexible leaves the Cloudflare-to-origin leg unencrypted and is not a durable default.

Two connections

flowchart LR
  U[Visitor] -->|HTTPS at the edge| E[Cloudflare edge]
  E -->|Chosen encryption mode| O[Origin]
ModeEdge to originDecision
FlexibleHTTPA constrained migration bridge; the origin leg is plaintext
FullHTTPS without strict certificate validationOrigin has TLS but cannot yet pass strict checks
Full (strict)HTTPS with certificate validationRecommended steady state; certificate must be valid and match the host

Release checks

Validate origin TLS

From a trusted environment, inspect certificate expiry, hostname, and chain without bypassing access controls. Do not “fix” a 525 by blindly lowering encryption.

Enable strict mode

Test one static URL and one dynamic URL that reaches the origin. A cached page alone cannot prove the origin leg works.

Define rollback

If strict mode fails, retain the timestamp, Ray ID, and origin TLS logs. Any temporary downgrade needs an owner and expiry.

Redirect loops

Flexible plus an origin-side HTTP-to-HTTPS redirect commonly loops. Draw the two protocol legs before changing redirect rules.

Primary sources

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