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What is a DNS query?
A DNS query is the request a client sends to get an answer about a name — an address, a mail server, a policy record.
A recursive resolver takes the question and walks the tree: root, then the TLD, then your authoritative nameservers, caching each answer for its TTL.
An authoritative nameserver, like ours, answers only for the zones it holds. It does not walk anything — it either knows or refers.
Most queries are answered from a cache somewhere in between, which is why a change is not visible everywhere at once and why the TTL matters more than the moment of the change.
An empty answer is not an error: NOERROR with no records means the name exists but has nothing of the type asked for. NXDOMAIN means the name does not exist at all.