Allow: Allows the client to log on to the pool. If you apply this setting, you must add block rules to prevent invalid client ...

Allow: Allows the client to log on to the pool. If you apply this setting, you must add block rules to prevent invalid client sign in.

Allow with URL: Allows the client to log on to the pool and presents the user with a message indicating that the user is using a client that is supported. The URL that you specify provides the message to the user.