IPv6 Nibble Prefix Length Check
Check IPv6 prefix alignment for whole-nibble reverse-zone labels; nonaligned prefixes do not imply a simple reverse-zone delegation.
Description
Check IPv6 prefix alignment for whole-nibble reverse-zone labels; nonaligned prefixes do not imply a simple reverse-zone delegation.
Each hexadecimal IPv6 reverse-zone label represents four prefix bits. This checker reports whether a prefix fits whole-nibble labeling.
When to use this tool
Check IPv6 prefix alignment for whole-nibble reverse-zone labels; nonaligned prefixes do not imply a simple reverse-zone delegation.
- Prepare the supplied prefix fields for this operation.
- Compare the complete example with the representation used by your own input before carrying the result into another step.
How to use the tool and how it works
- Enter prefix. Use the exact text syntax, units and index conventions explained below.
- Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
- Read result.nibbleAligned, result.labels. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Require prefix from 0 to 128. nibbleAligned is true when prefix modulo four is zero; labels is prefix/4 when aligned and null otherwise.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| prefix | prefix. | Integer from 0 to 128 inclusive |
| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.nibbleAligned | Flag for nibble aligned under the exact condition described above. |
| result.labels | The labels value under the stated formula or text convention. |
{
"input": {
"prefix": 64
},
"output": {
"result": {
"nibbleAligned": true,
"labels": 16
}
}
}Limitations and assumptions
- Alignment alone does not establish a valid DNS delegation. No address or zone is parsed.
- IPv4 input uses strict dotted-decimal octets without leading zeros or surrounding whitespace. IPv6 accepts its supported compressed or full spellings and trims surrounding whitespace, but rejects zone identifiers; embedded dotted IPv4 uses the strict IPv4 spelling. IPv6 address outputs are fully expanded unless stated otherwise.
- All declared input fields are required and unexpected top-level fields are rejected. Numbers must be finite; lists are limited to 128 entries and ordinary text fields to 8,192 UTF-16 code units, with tighter limits where stated.
- JSON text inputs must parse within bounded nesting and size limits. Numeric outputs outside the safe finite range are rejected; large exact integer results use decimal strings. Indexes and half-open spans are zero-based unless a rank is explicitly described as one-based.
Alternative or Complementary methods
Use address-set arithmetic for prefix planning and a routing or interface inspection for deployed configuration. Membership and overlap do not establish reachability, ownership or route preference.
References
Similar or alternative tools
- IPv6 Prefix Address at Offset
Select one IPv6 address at an exact zero-based offset inside a normalized prefix, including every address and avoiding 128-bit floating precision loss.
- IPv6 Prefix Address Offset
Return exact IPv6 zero-based address offset within a supplied normalized prefix, retaining null for nonmembers.