URL Length Limits

Today’s question is a simple one: “What is the maximum URL length supported by Internet Explorer?” And the answer, as befitting an IEInternals post, is surprisingly complicated.  The simplistic answer is that WinINET.h defines INTERNET_MAX_URL_LENGTH as 2083 characters, and this limit remains in force in a number of places. However, the true limit can be…

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What I’d like to see in IE12

As the holidays approach, I’ve decided to publish my “wishlist” for the next version of Internet Explorer. I’ve been pretty good this year, so hopefully the IE team will deliver some of these presents. 🙂 Please remember: I’m just an MVP, and I don’t have any magic powers that would guarantee that any of my…

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Debugging in IE10 on Windows 8

Emulating the “non-Desktop Experience” in the Desktop Experience The new full-screen “fast and fluid” experience of IE10 on Windows 8 offers many improvements over Internet Explorer 10 on the Desktop (ranging from UX to Security), but one thing it lacks is the F12 Developer Tools, used by web developers to debug web pages. While you…

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Understanding Protocols

For over a decade, Internet Explorer has enabled developers to extend the browser with new URL protocol schemes. These protocols can be one of two types: Asynchronous Pluggable Protocols – COM objects that implement the IInternetProtocolRoot interface and return content to URLMon, usually for rendering content inside of Internet Explorer or Web Browser controls Application…

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Integrated Windows Authentication

Inside Internet Explorer’s Tools > Internet Options > Advanced dialog, there’s an option named Enable Integrated Windows Authentication: This preference is stored using a REG_DWORD named EnableNegotiate inside HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings. When set to 0x1, Negotiate is enabled. From time to time, users have asked what this option does and why they’d ever want to adjust…

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Stylesheet Limits in Internet Explorer

KB 262161 outlines the maximum number of stylesheets and rules supported by Internet Explorer 6 to 9. A sheet may contain up to 4095 rules A sheet may @import up to 31 sheets @import nesting supports up to 4 levels deep Some folks have wondered about the math that underlies these numbers. The root of…

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A Primer on Temporary Internet Files

On Windows Vista and above, Internet Explorer’s Temporary Internet Files are maintained in two isolated WinINET cache containers. One cache is used for sites loaded in Protected Mode (Internet Zone and Restricted Zone) and the other cache is used for sites loaded outside of Protected Mode (Trusted Sites, Local Intranet, and Local Machine). Each cache…

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File Upload and Download Limits

Over the last few years, we’ve had a few questions about WinINET’s limits for file upload and download. I’ve summarized those limits in the following table:   Upload (total size) Download (per file) Internet Explorer 6 2gb 2gb (4gb for Chunked or Connection-Close transfers) Internet Explorer 7 2gb 4gb Internet Explorer 8 2gb 17,592GB Internet…

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SOCKS Proxies in Internet Explorer

We recently had a report over on the IEBlog that SOCKS proxies are not supported by IE9 Beta. That observation is correct, and a regression from prior versions of Internet Explorer; IE9 Beta simply ignores the SOCKS proxy if one is specified in the Internet Control panel. Update: This regression, introduced in IE9 Beta, was…

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Trivia: Animated GIF Timing

Every now and again, someone reports that Internet Explorer is “slow” when rendering an animated GIF file. Typically, they’ll load a lengthy animation in Firefox and IE and note that it runs much more quickly in Firefox. Similarly, Chrome and Safari are “slow” while Opera is “fast.” Conversely, there are bug reports against Mozilla complaining…

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