Fiddler is adding "Pragma: no-cache" headers

[pat.osterday]

I'm setting up a Varnish cache server and in my testing, I found that
Fiddler seems to be adding "Pragma: no-cache" headers to requests. At
first I thought I had something configured wrong, but once I closed
Fiddler, things started to work.

Could Fiddler be doing this? The request if for an image with a query
string:

http://{site}/re/image.jpg?OBJID=257114&COMP=26

Any ideas? I don't remember seeing this occur before, but I wasn't
looking for anything like this.

Thanks,
Pat

[EricLaw]

No, Fiddler does not add such a header, but you're not imagining
things either.

I explain how browsers (like IE) behave differently when a proxy is
present over here:
http://blogs.msdn.com/b/ieinternals/archive/2010/07/08/technical-information-about-conditional-http-requests-and-the-refresh-button.aspx.
Specifically, when you perform a "Refresh" operation in your browser,
if IE believes a proxy server is present (e.g. Fiddler), a Pragma: no-
cache request header is added. Similarly, if you perform a HTTP POST,
ordinarily, IE will send a Cache-Control: no-cache header on the
request, but if it detects a proxy is present, it will instead send
Pragma: no-cache.

-Eric

[pat.osterday]

Great information! Thanks so much!

Fiddler is awesome - one of the premier tools on the Windows platform!

On Oct 2, 1:37 pm, EricLaw <bay...@gmail.com> wrote:
> No, Fiddler does not add such a header, but you're not imagining
> things either.
>
> I explain how browsers (like IE) behave differently when a proxy is

> present over here:http://blogs.msdn.com/b/ieinternals/archive/2010/07/08/technical-info....