Scaling of ctdb & DNS round robin and scaling of pdc

[Johannes Amorosa | Celluloid VFX]

Hello List,
I hope this is the right place to ask - I have two questions:

1. In the ctdb wiki http://wiki.samba.org/index.php/CTDB_Setup it is 
recommended to use dns round robin for loadbalancing.
I'm quite new to this - how does samba handle a "session". We need 
massive I/O for our setup and considering ctdb to avoid our
smb bottleneck. When is the client getting a "different" IP- Address? 
Everytime a file is read or stored - our every morning when
you log into your workstation. If this is the case then loadbalancing 
would be quite random. The scaling figures in one of the PDFs
are impressive - are these "artifical" benchmark tests or real life scaling?

2. Can the PDC be a bottleneck. Can I avoid this with samba 4 and 
integrated PDC? I would like to here your opinion

Thank you for your time.
Johannes