Description
Return the low four bits of flags as rcode.
Packet headers encode several meanings in fixed-width fields. Bit positions, network byte order, and reserved values must be distinguished from validation of an entire message.
Return the low four bits of flags as rcode.
When to use this tool
Use DNS Header Rcode Low Bits when you need to decode or encode one explicit packet field.
How to use the tool and how it works
- Enter flags. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read rcode. Use the output convention below.
Return the low four bits of flags as rcode.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| flags | Flags | Required. Safe integer; minimum 0; maximum 65535. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| rcode | Rcode | Required. Safe integer. |
json
{
"input": {
"flags": 33155
},
"output": {
"rcode": 3
}
}Limitations and assumptions
- Extended EDNS response-code bits and their meaning are outside scope.
- 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 captured header and apply the relevant protocol's structural and state rules.
References
Similar or alternative tools
- Network: DNS Rcode Low High Field Join
Combine the eight-bit extendedRcode and four-bit headerRcode as 16 × extendedRcode + headerRcode.
- DNS NXDOMAIN NODATA Header Distinction
Classify RCODE 3 as nxdomain; RCODE zero becomes noerror-empty-answer or noerror-answer according to answerCount.