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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ARR Health Check sends too many requests too soon defying the configured interval

This is an interesting one, so wanted to blog on this. Had an Enterprise customer with an ARR that was keeping Web Servers very busy playing the Health Check ping-pongs by the seconds, even though ARR Health-Check interval was configured for 30 second. As a result, Web Servers were overwhelmed at times, and users were…

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Binding Multiple Sites With Single SSL Certificate

One of our Premier customers called me the other day needing assistance on running multiple web sites with a single SSL certificate using the same port. The idea was clever, especially when you have many several sites but only a handful of SSL certificates. But how do you solve this one-Cert-fits-all issue? There are two ways…

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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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Can't play PlayReady DRM video after installing Silverlight Update 5.1.31010

On December 9 Microsoft released Silverlight version 5.1.31010.  This version has been pulled and replaced with 5.1.30514. If you experience errors when trying to view DRM protected videos on sites like Netflix, Amazon Prime, or Sky, please check to see if you have Silverlight version 5.1.31010 installed and if so, uninstall and reinstall Silverlight. Uninstall…


Hosting multiple websites: IP or Host Headers?

IIS supports multiple Web sites on a single server. To create and host multiple Web sites, you must configure a unique identity for each site on the server. To assign a unique identity, distinguish each Web site with at least one of three unique identifiers:  an IP address, or a TCP port number or a…

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Suppress WAS Warnings Due to Regular IIS Application Pool Recycling

Attended a call of duty when a customer needed to suppress WAS (Windows Activation Services) warnings logged during regular IIS Application Pool recycling. Here is a short version of the warning: Log Name:      SystemSource:        Microsoft-Windows-WASDate:          9/30/2014 1:30:20 PMEvent ID:      5011Task Category: NoneLevel:         WarningKeywords:      ClassicUser:          N/AComputer:      XXXXX02Description:A process serving application pool ‘XXXX’ suffered a fatal communication…

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