I'm in that group you interviewed. Didn't know what perm-gen is although I've seen it in errors when java used up all memory. Next question was about Hibernate's different caching levels.

I've been rejected enough to eventually learn all these. Then finally when I got hired, questions were the very basic define static, inheritance etc.

I knew it was a matter of numbers and should not mind the devastating feeling of rejection. But damn, you can never know how it feels experiencing tons of rejection until you do.