Modulelessen (2/4)
NXDOMAIN e NODATA
NXDOMAIN and NODATA
For negative caching and resolution failures, see RFC 2308 and RFC 9520.
NXDOMAIN means the queried name does not exist. NODATA is a common description of a NOERROR response with no record of the requested type: the name exists, but that type is absent. Negative answers can also be cached.
| Does the name exist? | Does the requested type exist? | Conceptual result |
|---|---|---|
| No | Not relevant | NXDOMAIN |
| Yes | No | NOERROR with an empty answer (NODATA) |
| Yes | Yes | The requested RRset |
This changes the diagnosis. A mail domain may exist but have no MX record. A newly created host may still appear to be NXDOMAIN because that negative answer was cached earlier. Check the authority section too: it often includes the SOA used to determine negative-cache lifetime.
When comparing observations, record the name and type, server, timestamp, remaining TTL, response code, and whether the answer came from an authority or a cache.
Check your understanding
Choose the best answer. This quiz runs locally and sends no DNS queries to real domains.
The name exists but has no AAAA record. Which result is consistent?