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We have a SharePoint MOSS 2007 installation which has two different external hostnames. When inspecting the setup I've noticed that there are two Alternate Access Mapping Collections mapped to the same web application. Each AAM collection contains one url mapped to the default zone.

I can't see how AAM collections are mapped to web apps or even how to create a new AAM collection. I've always thought that there was just a one to one mapping between web apps and AAM collections.

Does anyone have any idea as to how you would create such a situation?

Cheers Russell

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up vote 0 down vote accepted

You can add new AAM collections using the "map to external resource" link in the AAM page in Central Admin. You shouldn't be able to have one of these new collections point to an existing web application though, that throws errors when you try to do it.

Can you maybe post a screenshot of your AAM page (with the "show all" view) so we can see what you are talking about?

Also, the best source for learning about how AAM works is:

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I've uploaded a screenshot here... I've blacked out all lines exceot the two lines which both point to the same web app (but are in different AAM collections) – Russ Giddings Jul 9 '09 at 16:23
Yeah, my guess is this was done with the "map to external resource" link. The only one that is truly pointed at your web app is the one that points to the actual URL for your app. The other still works because DNS points it to the same IP. – MattB Jul 9 '09 at 16:35
Ah, yep, thats looks like whats happened. Cheers for that! :-) I don't suppose you know how to delete these mappings to external resources once they have been created? – Russ Giddings Jul 9 '09 at 17:08
Think I need to use stsadm -o deletezoneurl :-) – Russ Giddings Jul 9 '09 at 17:10
It is even easier than that - once you are in a collection, click the "Edit Public URLs" link, and there is a delete button. – MattB Jul 9 '09 at 18:47

When you create an AAM you are doing it for a web application. Since a site collection is inside of a web application those site collections will also work with the mappings. If you have multiple web applications you will want to make sure that you mapped the correct ones.

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Hi there, cheers for the response but i think youre getting confused between site collections and Alternate Access Mapping Collections. I have one site collection in my single web application. The problem is I have two Alternate Access Mapping Collections associated with my single web application and I dont know how it got in to this state. :-S – Russ Giddings Jul 9 '09 at 16:05

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