Description
Remove one optional leading dot and require a hostname no longer than 253 characters with ASCII labels from one through 63 characters and no leading or trailing hyphen.
Web protocol data has several layers: a complete message or URL, individual fields or components, and the literal tokens within them. Delimiter presence, spelling, comparison rules, and parser normalization can affect results. A check of one component needs its stated scope before it can be used in a larger parser or policy decision.
Remove one optional leading dot and require a hostname no longer than 253 characters with ASCII labels from one through 63 characters and no leading or trailing hyphen.
When to use this tool
Use Cookie Domain Leading Dot Normalization when you need one stated URL, header, or protocol-component check in a diagnostic or parser workflow. Supply the input level specified below.
How to use the tool and how it works
- Enter domain. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read normalized, hadLeadingDot. Inspect hadLeadingDot before interpreting the associated values.
Remove one optional leading dot and require a hostname no longer than 253 characters with ASCII labels from one through 63 characters and no leading or trailing hyphen. Lowercase the result and return hadLeadingDot.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| domain | Domain | Required. Text; maximum UTF-16 length 8192. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| normalized | Normalized | Required. Text; maximum UTF-16 length 8192. |
| hadLeadingDot | Had Leading Dot | Required. Boolean. |
{
"input": {
"domain": ".Example.COM"
},
"output": {
"normalized": "example.com",
"hadLeadingDot": true
}
}Limitations and assumptions
- A trailing dot, repeated dots, and raw Unicode labels are rejected. This is a normalization subset, not a DNS lookup, IDNA conversion, public-suffix check, or a cookie-domain acceptance decision.
- The field tables state structural bounds; the mechanics also specify cross-field constraints. Malformed inputs and unsupported domains cause errors. A successful false flag, empty branch value, or zero placeholder has the meaning stated above and is distinct from an input error.
Alternative or Complementary methods
Use a complete URL or header parser when the task involves an entire field or message. Test actual browser, server, or cache behavior separately when a security or protocol decision depends on more than this component.
References
Similar or alternative tools
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