DNS Name Suffix Label Match

Check DNS suffix membership by complete labels with ASCII case-insensitive octet comparison; avoids misleading textual substring suffix matches.

Description

Check DNS suffix membership by complete labels with ASCII case-insensitive octet comparison; avoids misleading textual substring suffix matches.

A textual suffix can accidentally match part of a DNS label. Complete-label matching avoids that ambiguity.

When to use this tool

Check DNS suffix membership by complete labels with ASCII case-insensitive octet comparison; avoids misleading textual substring suffix matches.

Prepare the supplied nameJson, suffixJson 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 nameJson, suffixJson. 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.matches. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Parse nameJson and suffixJson as byte-label arrays. Require enough name labels and compare corresponding rightmost labels with ASCII-only case normalization.^[1]

Input field	Meaning and representation	Accepted input
nameJson	JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file.	Text
suffixJson	JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file.	Text

For the JSON text fields, the following decoded structures show the example records before they are serialized into input strings. Keep field names, list nesting and value types as shown.

json

[
  {
    "field": "nameJson",
    "decoded": [
      [
        65
      ],
      [
        98
      ]
    ]
  },
  {
    "field": "suffixJson",
    "decoded": [
      [
        66
      ]
    ]
  }
]

Output field	Interpretation
result	Object containing the named outputs below.
result.matches	Exact equality or membership under the specific rule above.

json

{
  "input": {
    "nameJson": "[[65],[98]]",
    "suffixJson": "[[66]]"
  },
  "output": {
    "result": {
      "matches": true
    }
  }
}

Limitations and assumptions

An empty suffix matches any valid label list. The result does not establish public-suffix boundaries, DNS ownership or resolver behavior.
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 a packet-aware DNS parser or resolver when the task requires compression-chain validation, live records or complete resource-record semantics. Keep byte labels, presentation text and network packets distinct.

References

Tool behavior and example: DNS Name Suffix Label Match — tool.io

Similar or alternative tools

DNS Name Longest Common Suffix
Find the longest complete DNS label suffix shared by two names under ASCII case-insensitive comparison, preserving the left name’s original octets.
DNS Label ASCII Case Normalizer
Canonicalize DNS ASCII uppercase octets only, leaving non-ASCII bytes unchanged; does not apply Unicode lowercase or IDNA mappings.