Description
Classify RCODE 3 as nxdomain; RCODE zero becomes noerror-empty-answer or noerror-answer according to answerCount.
A DNS response code and an empty answer section describe only part of a response. Establishing the reason an answer is absent can require authority data and query context.
Classify RCODE 3 as nxdomain; RCODE zero becomes noerror-empty-answer or noerror-answer according to answerCount.
When to use this tool
Use DNS NXDOMAIN NODATA Header Distinction when you need a cautious classification using only supplied DNS header facts.
How to use the tool and how it works
- Enter rcode, answerCount, authoritative. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read headerClass, nodataProven, authoritative. Inspect nodataProven, authoritative before interpreting the associated values.
Classify RCODE 3 as nxdomain; RCODE zero becomes noerror-empty-answer or noerror-answer according to answerCount. Other codes become other-error. Copy authoritative and always return nodataProven false.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| rcode | Rcode | Required. Safe integer; minimum 0; maximum 15. |
| answerCount | Answer Count | Required. Safe integer; minimum 0; maximum 65535. |
| authoritative | Authoritative | Required. Boolean. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| headerClass | Header Class | Required. Text; maximum UTF-16 length 8192. |
| nodataProven | Nodata Proven | Required. Boolean. |
| authoritative | Authoritative | Required. Boolean. |
{
"input": {
"rcode": 3,
"answerCount": 0,
"authoritative": true
},
"output": {
"headerClass": "nxdomain",
"nodataProven": false,
"authoritative": true
}
}Limitations and assumptions
- An empty answer alone cannot establish NODATA; authority records and response context are not analyzed.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Inspect the complete response, authority section, and original query before assigning a negative-answer meaning.
References
Similar or alternative tools
- DNS Header Rcode Low Bits
Return the low four bits of flags as rcode.
- Network: DNS Rcode Low High Field Join
Combine the eight-bit extendedRcode and four-bit headerRcode as 16 × extendedRcode + headerRcode.