DNS TTL explained

To interpret DNS TTL, follow the query through stub resolver → recursive resolver → delegation → authoritative nameserver. A recursive resolver can answer from cache, so a user response is not necessarily fetched directly from the authoritative server. TTL, record type and response code explain where the result came from and how long it can remain usable.

How to check the DNS result

Check the name and query type first, then the authoritative answer, then the chosen recursive resolver. NXDOMAIN, SERVFAIL, REFUSED and timeout represent different conditions. After a DNS change, compare authoritative data with several resolvers; clearing a local cache helps only when the stale answer is actually local.

The detail that matters

TTL is carried in DNS responses in seconds and tells recursive caches how long an answer may be reused. Lowering TTL before a planned migration can shorten future cache lifetimes, but already-cached answers keep the TTL they received earlier; negative answers can also be cached according to DNS rules. You can repeat the DNS check with 2ip DNS check.