DNS Resolution Visualiser
Network Fundamentals
Overview
A stub resolver checks local state and asks a recursive resolver. On a cache miss, the resolver may follow root, top-level domain and authoritative referrals. Cached answers respect TTL. NXDOMAIN means the queried name does not exist; timeout means an answer was not obtained. The existing topology resolver is deliberately simpler.
Protocol stages
- 1Stub resolver
- 2Recursive cache
- 3Root referral
- 4TLD referral
- 5Authoritative answer
Interactive exercise
Knowledge check
The recursive resolver has a valid unexpired answer in cache. Which operation is normally necessary?
Related practice
Lab: dns-failureEducational model — not real hardware, traffic or official certification.