Most effective means of PHP AD Authentication?

Our company is looking at moving authentication from our web app which is PHP running on Apache in Windows, and would like to authenticate using Active Directory. I have a way to simply pull your username that you're already authenticated with, but I have no experience with actually authenticating.

Reading up it looks like LDAP would be the way to go. My question is as follows:

Is LDAP the best way to authenticate 开发者_开发问答in a PHP web app using Active Directory credentials? Is there a different setup I should go to perhaps using PHP and IIS?

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http://www.davidschultz.org/2008/04/10/how-to-authenticate-against-active-directory-using-php/

^ this will show you how to authenticate against AD with PHP.

I don't know that this is better or worse than LDAP, but it seems pretty easy. Though, read through the comments first--it's probably not a good idea to hit AD on each page load but rather store a value somewhere to check against as one of the comments suggests.