I applied through an employee referral. The process took 2 weeks. I interviewed at Proofpoint (Sunnyvale, CA) in Aug 2013
Interview
Multiple interviews and a panel interview. Very easy questions about RAID, random linux commands, recovering dirty filesystems, etc. Questions about past experiences and experience with Puppet and what programming language I prefer. I chose Perl and was asked what my most used modules are. Extremely easy interview process.
Interview questions [1]
Question 1
The unexpected part was that there weren't any hard questions asked