I have a SharePoint 2010 installation at my customer looking a bit odd. We have three web applications (intranet, mysite and cooperation) in three different web applications on the IIS serving HTTP-requests on port 80. There is also a wild card SSL certificate installed on the server which can be used for any application under the domain *.customer.com.

There are also three other web applications on the server for HTTPS-requests on port 443 serving the same content in a different folders within C:\inetpub\wwwroot\ and of course a web application to serve Central admin.

Coming from the ASP.NET-world this setup seems odd, since I would – just add a binding on port 443 to serve HTTPS-request on the same web application serving HTTP-requests on port 80. So instead of having seven web applications, with redundant files, I would use only four.

But I’m kind of new to SharePoint, and there might be something I’m unaware of… What am I missing in this setup?

2 Answers 2


It could easily explainable by the concept of "Application Extension" in SharePoint, which is simply a mechanism that creates a new Web Application (it could be the same Host header too, but different Protocol, HTTP vs. HTTPS - with the purpose of offerring different authentication mechanism to different targeted people, e.g. Intranet vs. Extranet, Employees vs. Partners). Possible scenarios could be many but for your reference: 1. People in Intranet access using Windows Authentication under a different URL the site whereas Partners require Forms Authentication 2. Content Publishers in a Publishing farm use Windows (NTLM/Kerberos) via HTTP whereas Regular Site visitors rely on SQL back-end for User data storage and connect via Forms-based authentication.

The bottom line - SharePoint creates a new Web Application every time you choose "Extend" in the ribbon with the added benefits of a application pool separation, variations in Protocol, URl or authentication mechanisms. You should see all these under Alternate Access Mappings in SharePoint, with a maximum of 4 Zones where one could map it.

Also another concept is the Host-Named Site Collections, that function a little bit different.

  • Thanx! This makes sence. There is an ISA for access to the intranet over HTTP where staff uses Form Authentication when they are not within the network, such as their home or on travel. I imagine this is the case here for two different Web Applications on the IIS originated from SharePoint alternative access mapping.
    – Benny Skogberg
    Sep 13, 2012 at 6:59

Well technically there's nothing with this setup. If I understand you correct, there's 2 folders on disk for a single web application? One for the HTTP binding and one for the HTTPS binding?

The person who configured this probably has setup the sites as HTTP first. Later on, they decided to add HTTPS to the party. To add the https url, the web application was extended, which means a second instance in IIS is created along with a second folder.

This isn't nescessary, you can indeed just add a SSL binding to the site. You should also create an alternate access mapping to map https to the site in that case.

A second option is that they decided to split http and https into different application pools for some reason, that would of course require two web applications as well. Why you would do this, I don't know.

So if I should take a guess; the person configuring this probably didn't know better :)

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