I am getting ready to extend a Web Application to another IIS Web Site so that I can use different forms of authentication between internal and external users.

When I do so, I have the choice of which Zone to place the web site in. Thus far, for any "Zone" field, I have just used "Default", but of course, when extending the web application, I have to choose a different Zone.

I have not been able to find any documentation on the differences between the five zones of "Default", "Intranet", "Internet", "Custom", and "Extranet".

In particular, I have trouble seeing what the difference between "Internet" and "Extranet" would be for a public facing URL.

What are the differences between these Zones?

1 Answer 1


These zones, and their labels, are just labels. There is no functional difference between the five. However, these labels indicate to the next administrator how they are used, and what they are for. You may not need more than one zone to use different authentication methods. In fact, Microsoft "recommend that you implement multiple authentication methods on the default zone", which makes access simpler for the user since only one URL is used.

To understand the connection between internal URL, zones and public URL the article A guide to Alternate Access Mappings Basics in SharePoint 2013 is very useful. The article describes zone in this way:

Zone is a label representing a Public URL, the zone is used to ‘connect’ an Internal URL to a Public URL. The zone names has no relation what so ever with the four Internet Explorer security zones (Internet, Local Intranet, Trusted sites and Restricted sites) and could just as easily been named 1,2,3,4 and 5.

  • 3
    Actually, this isn't quite correct. For example, Outlook prioritise the Intranet Zone over the Default Zone when determining which URL to use for a connected list. Steve Peschka's blog also mentions a number of other considerations pertaining to Search: blogs.technet.com/b/speschka/archive/2013/06/26/… Commented Mar 20, 2014 at 16:11

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