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In Depth Information
Alternate Access Mapping
When you initially install and start using SharePoint, accessing it by using the NetBIOS name of
the server works fine, but what if you want your users to be able to access it the same way they
do other Web sites or be able to access it from the Internet? You can’t resolve that server name
among all the other machine names on the Internet, so you need it to resolve to a DNS name.
Alternate Access Mapping (AAM) is about mapping a SharePoint web application to an alternate
address other than the default. This way, you can have an internal, default name of http://spf2
and an Internet URL of http://SharePoint.dem0tek.com, both pointing to the same server
(and more importantly, to the same content).
AAM specifies alternate access to a web application by internal URLs, public URLs, and
zones. An internal URL is what the web application responds to. A public URL is what the web
application returns to the user in the address bar and in the links for all search results. Web
applications can have five public URLs associated with it (at which point they are called zones ).
So, you can have a Default zone (that’s the default URL for the web application, which is the root
path for all the site collections it might contain), an Intranet zone, Internet zone, Extranet zone,
and a Custom zone.
There is also another use for AAM—extending web applications. An extended web
application is just an IIS Web Site that points to the same content database as an existing web
application. This is done if you want to use some other URL, security settings, or authentication type
to access the same data (essentially if you want to use different IIS Web Site settings to access
the same content, like anonymous or Kerberos). That way, users can have more than one way to
access the same data, especially if you want to have different types of authentication for the
content, depending on what URL the user uses.
Because an extended web application is just sharing the same content database as an
existing web application, it is considered just another URL used to access the first web application’s
content. This is why an extended web application is not given its own name in the web
application list but is considered a zone of the existing web application. In that case, one of the public
URL zones is taken up with the URL of the extended web application. You might want to note
that there are a limited number of AAM zones available to extend (Intranet, Internet, Custom,
Extranet) per web application. The Default zone is the original web application’s URL, so
obviously that is not available to be used for extending.
So, when planning your URL structure and how users are going to access SharePoint, keep
AAM in mind.
When planning for SharePoint, it’s a good idea to keep in mind how you would like to structure
your site collections. Site collections are composed of a top-level site and all the sites that stem
from it (called subsites ). The top-level site is usually accessed by using the web application’s URL
and then the path to the top-level site’s home page. When creating a site collection, you must
decide what its URL path will be. When you create your first site collection in a web application,
you can give it the root address for that web application, or you can specify a path. What this
means is if you create the first web application on server SPF2, then its URL can be http://SPF2,
using port 80, which is the root address for the URL. But if you create a second site collection in
that web application, it needs to have a different path, because it can’t use the same URL. This is
where managed paths comes in. By default SharePoint has a sites wildcard managed path for