If you zipped through the default settings when configuring DirectAccess, or worse, used the Getting Started Wizard, chances are that your Network Location Server (NLS) is running right on the DirectAccess server itself. This is not the recommended method for using NLS; it really should be running on a separate web server. In fact, if you want to do something more advanced later, such as setting up load-balanced DirectAccess servers, you're going to have to move NLS onto a different server anyway, so you might as well do it right the first time.
NLS is a very simple requirement, but a critical one. It is just a website, it doesn't matter what content the site has, and it only has to run inside your network. Nothing has to be externally available. In fact, nothing should be externally available, because you only want this site accessed internally. This NLS website is a large part of the mechanism by which DirectAccess client computers...