I've read a lot about the Kerberos protocol and lately some about Kerberos authentication in SharePoint, how you must configure this and that (SPN) to make it work.
So now I've taken time to test this, and guess what -- Kerberos authentication works fine without SPNs etc. I configure web applications to use classic or claims-based authentication, but there is not difference from when configure them to use NTLM.
I've been iisresetting, restarting, loggin in and out, using several web apps, different accounts, etc, etc, using web parts with links and such to other web apps and so forth, accessed the site from different machines, etc, but I cannot have the site not functioning properly for me.
(This is a virtual Active Directory environment with Windows Server 2008 R2 and Windows 7 machines, and SharePoint Server 2010 SP1.)
What am I doing wrong, I just can't get this Kerberos authentication to not work. ;-)