Hi! We are planning to create two sharepoint web applications using SharePoint 2010 Enterprise Edition. All Users that have access to web app 1, should also be able to access web app 2. This authentication shall be powered by server 2003 active directory. -- do I need to use claims based authentication? If so -- can I use Windows Based Authentication with NTLM for that? The only thing I really want is that users navigating from web app 1 to web app 2 (and vice versa) do not have to authenticate twice. I do NOT want to configure Kerberos if it is not absolutely necessare though... Can you give me any hints? Thanks!