Also, I wonder how you learn all these knowledge (that is, asking for recommendation on a few books/resources for learning) if you don't mind sharing. Thanks in advance!
During the interview process at Google we don't expect candidates to be able to get to this level of depth, but we try to hire candidates that could, over time and depending on their skill set, potentially reach a similar level of depth and ability to troubleshoot cases.
I'm one of the TSEs who handle networking cases. True to what was said, I was hired with very little networking background, but plenty of development and hardware information.
I've since taken the mantle for handling most of the cases dealing with Interconnects and VPNs. I enjoy it too!
Oh, yeah, we're hiring: https://careers.google.com/jobs/results/?company=Google&q=Te...