Cache / CDN query-string friendliness (headers)

What to fix

Tune cache / CDN so marketing query parameters are not ignored when HTML is cached.

Step-by-step fix

1. In Cloudflare / Fastly / host CDN, open the cache rule for HTML on the landing path.
2. Include utm_source, utm_medium, utm_campaign, utm_content, utm_term, gclid, fbclid (and your click IDs) in the cache key — or bypass cache on those params — according to your CDN’s documented pattern.
3. Avoid “ignore all query strings” for the HTML path you advertise.
4. Purge HTML for the landing URL and retest with UTMs.

Choose the path for your setup

• WP Rocket

  Use “cache query strings” / rejected parameters lists carefully so marketing params are not stripped from the cache key.

Confirm it is fixed

Re-scan and re-check C14 headers after the cache rule change.