IIS Services: HTTP.sys, W3SVC, WAS, W3WP, oh my!

When client makes an HTTP request to IIS, there are many layers of drivers and services it travels through. In this blog, I wanted to give a high level overview of the major layers showing how they fit altogether. Here is the high level flow: HTTP.sys is the Kernel-mode HTTP/HTTPS protocol listener. HTTP.sys listens for…

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Hunting Down a Classic Error: “Page Cannot be Displayed”

Was assisting a customer on a critical server-down situation with a very generic error: “Page cannot be displayed….”. This is a classic error and puts you on an open-ended troubleshooting venue. One of the things you want to do first is to ask yourself few questions: Wasn’t this Server working fine when it restarted last…

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SSL Certificate Disappears After Binding into IIS site

Just the other day, I was engaged with an Enterprise customer while he was experiencing an SSL Cert déjà vu, it was disappearing from the IIS binding. It was interesting for sure, and hence the preclude for blogging it! First thing first, what’s the error message here? An event similar to the following is logged in…

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Should I worry about Timer_ConnectionIdle entries in HTTPERR Log?

While helping customers troubleshooting HTTP-related error, a common question that we face: What is Timer_ConnectionIdle (as we see a lot of them in the HTTPERR log)?, and is this something to worry about? Here is an excerpts from the HTTPERR log: 2016-07-05 18:45:09 172.31.77.6 2094 172.31.77.6 80 HTTP/1.1 GET /qos/1kbfile.txt 503 – ConnLimit 2016-07-05 19:51:59…

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