Networking Interview Questions

Unanswered Question
Mar 24th, 2010

I have taken lot of interviews and guys who are having 3 -5 years experience doesn't know about the basics. One interested answer was being given to me after asking a question about subnetting that I always use subnet calculator. This is really embarrassing that we are claim about our expertise and don't even know basics. So finally I made my mind to teach people not by giving them answers but by giving them questions. Once people read the basic questions then they come to know how much they know.

Basic Cisco questions

Basic Cisco BGP questions

I would be happy to get your feedback.


shivlu jain

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Collin Clark Wed, 03/24/2010 - 11:23

I've been in networking for over 10 years and I always use a subnet calculator. It's not because I don't know how to subnet, but using a calculator is faster and eliminates any errors. You may be frustrated with people not knowing 'basic' questions about the protocols used in your environment, but you can't expect them to know OSPF if they've only used EIGRP. We recently hired someone that knows OSPF inside and out but we run EIGRP. Why did we hire him? Because you hire the person not their current skill set. A good person can and will learn your environment. IMO some of the BGP questions are above CCNA/CCNP level

burleyman Wed, 03/24/2010 - 12:20

I would have to agree with Collin. Albert Einstein once said "Never memorize what you can look up in books. ". That would hold true for subnetting. Now with that said I personally can do most easy subnetting in my head and use that just for meetings and discussions, when I am ready to put it to use I always verify my self using a subnet calculator. Now if I was in an interview and maybe a little nervous I might stumble doing it in my head. When I got into the IT field 9 years ago after 22 years of being a Machinist/Quality Engineer I had no real world experience in networking but I understood processes and root cause analysis. When I was interviewed for my current position in IT, I think it was probably the most realistic and best interview I had been through. What the manager did was to ask some basic questions, What class IP address is this? What was the Printer and Keyboard IRQ (this was his favorite question...still don't know why)? Then he would ask some basic troubleshooting questions like, If a helpdesk ticket came to our group that a user could not get connected to the network what would be the steps in order you would do to try and resolve quickly? What would you do if a user said "The Internet is down" what would you do? If you passed those he would have you sit with a couple of the people you would work with and they would give you a couple actual tickets that they had already resolved and gave then to you written as they came in to them and asked you to talk them through what you would do to resolve? I passed them so quickly that they gave me a ticket they were working on that had them a little stumped but did not tell me that. I rattled off what I would do and right at the end they said "I did not think of looking at that". I resolved the problem and got the job.....with no real world experience. Now while I had no real experience I did take 2 college classes, I took and passed my A+, Network+, MCP, and CCNA after I took a CCNA bootcamp. Now I am responsible for our network infrastructure world wide and love it. Now could I talk about BGP, OSPF, EIRGP off the top of my head in but give me a few minutes I could track down the problem and what to do to fix it.....well not a few minutes for all problems but I think you get the point. What good does it do to have all that memorized in depth be pretty sure of my response when in a minute I could look it up and be 100% sure of my answer.


shivlu jain Wed, 03/24/2010 - 22:49

Thanks guys for your answers. I really appreciate your concern that we don't belong to the scientists family and could not get into the depth. Regarding subnetting if we subnet calculator it doesn't mean we don't know anything but my concern is that during interview if I ask any questions about subnetting rather answering those questions I am getting reply that I usually use subnet calculator. This is the attitude which is not acceptable during interviews. The candidate should say that give me a minute let me calculate. The same way if question on OSPF is asked and Interviewer received a answer that I usually use cisco doc cd to get all the designs and answers. I think you guys have taken into otherwise. I am posting this only in terms of interviews not for real life scenarios.


shivlu jain

rgodden Wed, 03/24/2010 - 23:00

I would expect a candidate to ask for a pen and paper or even white board

an explanation. No point pressing buttons on a calculator if you dont know what they


shivlu jain Wed, 03/24/2010 - 23:10

Yes you are absolutely right. The same is always given to candidate by me . Don''t know about others.


shivlu jain

burleyman Thu, 03/25/2010 - 04:56


I agree with you, if someone during an interview said well I always use a calulator and that was it, possibly the wrong person. My answer would have been, can I have a piece of paper and pen, and then worked it out and then stated but I always check my work with a subnet calulator to make sure I did not make a mistake.


ravindu_r Thu, 02/23/2012 - 22:55

HI Shivlu,

Good collections of questions.

I went through questions on both the link, could answer most of them, i just want to verify my answers and also want to know the answers of questions which i was unable to answer, it will be great if you share answers of all the questions in the links.



Cisco_Learning_... Fri, 02/24/2012 - 10:05

Great Thread, just a quick FYI about the changes happening later today.

Friendly Reminder: Effective this Friday, February 24th, at 5:00 p.m. (PT) all new discussion thread requests will be redirected to the Cisco Learning Network.  We encourage you now to go there to create any new discussion thread or document regarding Certifications and/or Training topics.  You may also refer to our jointly created FAQ.


This Discussion

Related Content