I often wondered about typical networking interview questions, there is a section of questions which is repeated no matter which company you prepare for and still found a lot of guys not sure about it. It does not mean you do not know networking, but then often an interview is conducted in a short interval and by no means someone is going to assess how good you’re in networking.

Still, the interview is used to measure how good/quick you think in a particular direction, there are other woes obviously like;

1. What is IPSEC?

I have seen questions like this, as I see it – this is just as absurd as it can get. The whole of interview is probably what ‘an hour thingy’?, I can go on answering for the above question for full one hour. That is to mean the question is not in quantifiable terms. I mean, do you think all the times, you’d be able to explain what exactly the interviewer has in his minds? that is a big Bull! If the question is posed at like “Explain the phases of an IPSEC VPN” – this is much easier to quantify answer-wise.

Coming back, couple of questions I have seen others keep asking and I myself have asked and haven’t gotten a satisfied answer many more times are like these;

1. Explain and differentiate Routed and Routing protocols?

2. Private IP addresses can’t be routed through internet, why?

3. What is ARP and how does it work?

4. Classful & Classless concepts?

5. TCP 4 way handshake – (this is best, as everyone seems to know the 3 way) ?

6. What is NAT-T ?

7. Different types of firewalls? (everyone knows ‘Stateful’ and ‘Stateless’, but nothing more – reason? they’ve studied it only once, not up to speed on the technology advances).

8. How does a device know that the destination is *not on the local network* ?

9. Can 2 VLAN’s have the same IP Subnet? – Most of them answer ‘NO, a BIG NO’ ?

10. Why/When a network loop happens in an L2 network?

These are pretty basic questions for Network/Security Engineer with 3 to 5 years experience as I see fit. So it kinda got into habit of me to shoot off from these and if majority is ‘no’ then the candidate is a big ‘no no’ for me!

Actually it even gets funny some times. I had a friend (who’ll read this as well ), he actually asked a guy to give some basic test cases for a cell phone/Mobile phone. So he gave some ‘not-so-satisfying’ test scenarios. So my friend asked him to write down a stress test case for this phone and the candidate mentioned that he will “Make a long distance call” and that was a stress test case for him. See the thinking has to be aligned if not exactly correct. Once a CCIE guy was just goofing around, since he only had teaching experience and never touched a live network in his life, so I was frustrated with this answers (C’mon if a router doesn’t respond, he’d just reboot it seems!) and so was my other fellows listening to it. So I asked him to subnet a network and asked him to use the white-board since he’d be more comfortable that way since he was a network teacher/instructor. He did something and came down on something silly as 90/2 is approximately 40. I was literally “DONE” with the candidate, went to my manager and asked him to just get this guy off the premises.

This post is not to insult anyone, see they all are equally working in this industry but then for everything there is a bench-mark. Hiring a candidate doesn’t stop there, the responsibilities to shoulder only starts from there –> To make him to full-fledged and productive on the project.