2 min readAn original planning guide. Use the linked primary documentation for platform details and the supported procedure for your environment.
Make queries comparable
Write the same hostname and record type for each observation, along with time, resolver, and the returned value.
Check the authority
Compare answers from the zone's authoritative nameservers. If they disagree, resolve that configuration question before blaming client caches.
Check cache context
Compare recursive answers and remaining TTL where available. A previous cached value can differ from the current authoritative value.
Test the application separately
Verify the actual hostname, protocol, and response after resolution. A correct DNS answer does not prove the web application is healthy.
Worked scenario
See the plan in practice.
One visitor uses the apex name while another uses www. Correct that comparison before interpreting the different destinations as propagation.
Review your result
Your acceptance checklist
Queries match- Authority checked
- Application tested
Use these checks to identify gaps in your dns comparison worksheet. Assign an owner to any unresolved item before the next dependent step.
The terms behind the task
- DNS cacheA temporary store of DNS answers kept to avoid repeating the same lookup immediately.
- DNS propagationAn informal name for the period in which changed DNS data becomes visible through different servers and caches.
- Recursive resolverA DNS service that finds an answer for a client by querying other servers as needed and usually caching results.
Primary references
For the underlying concepts and current platform details:
