Requests not always using the Proxy Url

Question

I have a map viewer that has the following settings-

esri.config.defaults.io.proxyUrl = "/proxy.ashx";
esri.config.defaults.io.alwaysUseProxy = true;

But when I look at the network trace in IE, some URLs are using the proxy and some aren't.  What would be causing this?

For example I see:

https://localhost/proxy.ashx?https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/legend?f=json&callback=dojo.io.script.jsonp_dojoIoScript8._jsonpCallback
https://localhost/proxy.ashx?https://[server name]/ArcGIS/rest/services/Org/Basemap/MapServer/legend?f=json&callback=dojo.io.script.jsonp_dojoIoScript6._jsonpCallback

then later I see

https://[server name]/ArcGIS/rest/services/Org/Basemap/MapServer/4/images/714F5E24

AD · Answer

I did narrow it down to the TOC and legend features.  If I commented those out, then the "invalid" URLs go away.

I am using IE 9 for this troubleshooting.

I found this thread that seems to be similar, but I don't like the answers included.  It sounds like an issue with the JS API that should be addressed.

http://forums.arcgis.com/threads/42803-Legend-Dijit-Problem-in-Internet-Explorer-(IE)

AdrianMarsden · Answer

IE8 & 9 but reading the Wiki entry (you learn something every day, thanks) even 9 seems not to fully support this.

Anyway, not to hijack the thread, the real question is why do these requests not go very the proxy page and get a token added?

Cheers

ACM

JeffJacobson · Answer

...in chrome, however, the source of the image looks like this

src="https://us.v-cdn.net/6038851/uploads/attachments/image_comment-648589-1.png" more like this>"

and it works without the token, where as in IE it is a proper path to the image (like your example src="https://[server name]/ArcGIS/rest/services/Org/Basemap/MapServer/4/images/714F5E24").

What's going on here then?

Which version of IE are you using?  Since older versions of IE do not support the Data URI scheme, it may be the case that the JS API is determining the URL format based on your browser.