The person in charge of the metrics analysis in our organization has told me she has to do some filtering on requests for PDFs to separate views of pages in the PDF (in the browser I assume) and the initial download of the file. Does this make sense to anyone? Does anyone have any documentation on this? She called it a "506 return code" but the HTTP 506 code doesn't seem like it would apply here.

  • You can try it and see for yourself by doing this this in your browser and using a tool like Firebug or the built in developer tools to view the HTTP requests your browser makes.
    – John Conde
    Oct 18, 2016 at 14:12
  • I tried this and the Live HTTP Headers plugin for Firefox but didn't see the 206 requests. Maybe my PDF was too small.
    – hofo
    Oct 18, 2016 at 19:17
  • 5xx are error codes - so that would not be a good thing to see. 2xx are "success" codes.
    – MrWhite
    Oct 18, 2016 at 19:23

1 Answer 1


I'd say it's more likely to be a 206 (Partial content) code.

One PDF = one resource. But if the file is large and both the browser and the server support range requests, the file can be fetched over a sequence of multiple requests. (RFC 7233)

  • That's the one. I looked at the IIS logs and found them.
    – hofo
    Oct 18, 2016 at 19:17

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