Read Content-Range on an unsatisfied request

The useful distinctions

• Content-Range relates response content to the complete representation.
• The unsatisfied byte-range form uses an asterisk before the slash.
• The number after the slash can communicate the complete length.

Read the slash as a boundary

An interval request can be perfectly well formed while falling outside the chosen object. In the synthetic example the object contains 2400 bytes, so its highest byte offset would be 2399. Asking to begin at 3000 cannot select any of those positions. The response therefore gives useful boundary information without supplying an alternative block. Write the advertised complete length into the diagnostic note and leave the received-media interval empty.

Use the information without guessing a repair

Do not turn the 2400 figure into an automatic request for the last 2400 bytes. First establish why the caller believed offset 3000 existed. A stale index, a changed object, a truncated upload, or a different negotiated representation are distinct hypotheses. Compare representation identifiers and resource selection before changing offsets. If a later authorized observation reports a new complete length, retain both values instead of overwriting the first. This preserves the sequence of evidence and helps distinguish a changing publication from an arithmetic error. A server response alone does not establish which publishing component supplied the wrong assumption. For this worksheet, preserve the original requested first offset of 3000 alongside the reported length. That pair explains the mismatch more clearly than replacing the failed request with a guessed correction.

Worked example · synthetic

The object length is 2400 bytes. The asterisk means that this response does not describe a satisfied byte interval; it does not request or promise all bytes.

Synthetic text example; no network operation has been performed.

HTTP/MIME line endings are CRLF. Request URL context, where labelled, is commentary rather than a wire field. No message was transmitted.

HTTP/1.1 416 Range Not Satisfiable
Date: Sun, 08 Nov 2026 08:00:00 GMT
Content-Range: bytes */2400
Content-Length: 0

Check the interpretation

• Check whether the requested first offset exceeds length − 1.
• Compare validators before reusing an old index.
• Do not interpret 2400 as a returned body length.