Key details

  1. Cloud CDN announced CDN-Cache-Control support on August 17, 2026.
  2. The header is standardized by RFC 9213.
  3. Its purpose is to target CDN/shared caches without changing browser-level caching.
  4. Google publishes separate cache-control header precedence guidance.
  5. Standards compliance does not guarantee identical behavior across every CDN.

What builders should take away

  1. Use CDN-Cache-Control when you need a different edge TTL or revalidation policy from the browser-facing Cache-Control header.
  2. Document and test header precedence in integration tests, especially if you also use s-maxage, Surrogate-Control or provider-side cache rules.
  3. For multi-CDN setups, run the same response through each provider and verify which directives are honored before relying on portability.
  4. Monitor cache-hit ratio and stale-content behavior after rollout instead of treating a standards-based header as self-validating.

What changed

On August 17, 2026, Google Cloud announced support for the targeted CDN-Cache-Control HTTP response header defined by RFC 9213. Origins can now send cache directives specifically for Cloud CDN edge caches without forcing the same directives onto browsers.

Why it matters

Applications often want long shared-cache lifetimes at the CDN while keeping browser caches shorter or more conservative. A standardized targeted header reduces the need for provider-specific cache configuration and makes origin-controlled cache policy more portable across supporting CDNs.

Browser and shared-cache policy can diverge cleanly

With CDN-Cache-Control, an origin can keep ordinary Cache-Control appropriate for user agents while expressing a separate policy for CDN caches. That is useful for frequently redeployed static assets, API responses and pages where edge reuse and client freshness have different requirements.

Header precedence still matters

Google documents precedence among targeted and general cache headers. Builders should test the exact combination they emit rather than assuming CDN-Cache-Control always overrides every other cache rule or product setting.

RFC support improves portability, not uniformity

RFC 9213 standardizes the header shape, but providers can differ in supported directives, defaults and product-specific behavior. Multi-CDN deployments should validate each vendor independently.

Timeline

2026-08-17

Cloud CDN adds CDN-Cache-Control

Google announced support for the RFC 9213 targeted cache-control header.

What to watch next

  • Whether Google expands support for additional targeted cache-control directives.
  • Adoption of RFC 9213 across other major CDNs.
  • Edge cases involving precedence between origin headers and Cloud CDN cache settings.

Still unclear

  • Directive support and precedence differ among CDN vendors, so behavior should not be generalized from Google Cloud alone.
  • Existing cache rules configured outside the origin response can still affect final caching behavior.

Sources

Direct reading behind this dossier.

3 sources