If-Range
The If-Range HTTP request header makes a range request
conditional: if the condition is fulfilled, the range request is issued, and the
server sends back a 206 Partial Content answer with the
appropriate body. If the condition is not fulfilled, the full resource is sent back
with a 200 OK status.
This header can be used either with the Last-Modified validator or
with ETag, but not with both.
The most common use case is to resume a download, to guarantee that the stored resource has not been modified since the last fragment has been received.
| Header type | Request header |
|---|---|
| Forbidden header name | no |
Syntax
http
If-Range: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT
If-Range: <etag>
Directives
- <etag>
-
An entity tag uniquely representing the requested resource. It is a string of ASCII characters placed between double quotes (Like
"675af34563dc-tr34"). A weak entity tag (one prefixed byW/) must not be used in this header. - <day-name>
-
One of "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", or "Sun" (case-sensitive).
- <day>
-
2 digit day number, e.g. "04" or "23".
- <month>
-
One of "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" (case-sensitive).
- <year>
-
4 digit year number, e.g. "1990" or "2016".
- <hour>
-
2 digit hour number, e.g. "09" or "23".
- <minute>
-
2 digit minute number, e.g. "04" or "59".
- <second>
-
2 digit second number, e.g. "04" or "59".
GMT-
Greenwich Mean Time. HTTP dates are always expressed in GMT, never in local time.
Examples
http
If-Range: Wed, 21 Oct 2015 07:28:00 GMT
Specifications
| Specification |
|---|
| HTTP Semantics # field.if-range |
Browser compatibility
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