See what one DNS cache can know
Place an authoritative change and a later observation on one resolver's cache timeline. The model never looks up a domain and never reports a global propagation percentage.
One resolver, one cache entry
Timeline result
The cache is fresh at the observation time, with 180 seconds remaining.
- Stored response
- stored positive answer
- Cache state
- fresh
- Remaining TTL
- 180 seconds
What this resolver can do
The resolver can return its stored positive answer without contacting authoritative DNS.
The authoritative change has happened, but this resolver can still answer from its stored positive answer.
Text timeline
- 0 seconds: One resolver stores a positive answer for 300 seconds.
- 60 seconds: The authoritative data changes.
- 120 seconds: A client asks this resolver; 180 seconds remain on the stored TTL.
- 300 seconds: The original stored TTL reaches zero.
Model boundaries
- This is one resolver cache, not every resolver, browser, operating system, or application cache.
- Negative caching uses a scenario TTL; production behavior depends on the authoritative SOA data and resolver implementation.
- Reaching zero makes refresh possible. It does not prove a query occurred immediately or that every observer now sees one answer.
- Resolver policy, serve-stale behavior, failures, and intermediate caches are intentionally outside this first model.
Continue with DNS TTL, positive caching, negative caching, and propagation for the protocol evidence and operational caveats.