How can I tell the difference when changes are not visible?

DNS propagation usually shows different answers across resolvers, while CDN cache usually serves stale content after DNS resolution is already consistent.

Can HTTP headers help tell the difference?

Yes. Cache hit indicators, Age headers, and Cache-Control behavior often point to CDN caching rather than DNS.

If DNS looks correct but some users still see the old site, what should I suspect?

Start with CDN edge cache, browser cache, and service worker cache before assuming DNS is still the problem.

CDN Cache vs DNS Propagation

How to tell whether delayed changes are caused by DNS propagation or cached CDN content, and what to check first.

Diagnose your site now

Problem

You changed configuration or content, but some environments still show the old result.

Symptoms

Some resolvers show new DNS answers while others still return old ones.
DNS looks correct, but the actual page content is still stale.
Update visibility differs by network or region.

Top 3 Causes

Real DNS propagation delay - Resolver cache and TTL still prevent consistent DNS answers.
CDN edge cache remains stale - DNS is correct, but cached content is still being served.
Browser or service worker cache remains stale - The client side still reuses older assets or content.

Diagnose with DechoNet

DNS Propagation Check to compare resolver answers.
DNS Lookup to inspect the current record and TTL.
HTTP Check to inspect cache headers, final response behavior, and content delivery path.

Resolution Checklist

If propagation differs by resolver, treat it as DNS propagation first.
If propagation is consistent but the page is still stale, investigate CDN or browser caching.
Check Age, Cache-Control, and CDN cache headers in the HTTP response.
Purge or invalidate CDN cache when needed.
Re-run both DNS and HTTP checks to confirm which layer changed.

When to Escalate

Escalate to platform owners if CDN purge rights or edge rules are not under your control.
If a deployment changed both DNS and CDN simultaneously, split the investigation by layer before acting.