When I attended the first interview with a networking company, at Menara Citybank, I had no idea what to prepare and what to study. What I knew was to bring my certificates and a CV. I thought that my 4 years of working experiences with a TelCo are adequate to answer all the questions by the panel. But I was wrong. The questions were quite general and most of them are theories/practical that I never went along before. Finally, I failed to get that job…

Two months later, I attended for another interview. My CV was passed to the Engineering Department Manager by my friend who is working with the company. I was called and I prepared myself with all the networking knowledges. Fortunately, I was short-listed for the second interview with the Vice President of Technology. Not much on technical knowledge, but more on softskill and my view on the technology itself. It was a good conversation with him and I probably could answer his questions firmly although after got provoke many times. Finally, I got the offer but I rejected due to the counter-offer from my current company. I was promoted to be a manager!!

A week later, another TelCo called me for an interview. This time, the panels were from Japan. I was quite nervous but still confident that I can perform well like the previous interview. The HR (EMERIO) asked me to prepare more on the technical Q&A. At the same time, I printed all my certificates and also my CV and binded them together like a thick A4 business proposal (ahhaha..I’m going to sell myself). During the interview, the panels only asked about my working experiences and how do I handle people and problem. Again I was lucky, they offered me to join them before going for the second interview session. After a series of istikharah, I decided to make a big change in my life…. I accepted the offer.

So, I would like to share the interview questions for Network Engineer to all the n/w engineer out there. You might increase your confident level if you know how to answer below questions. Be prepared!!!

General Knowledge Questions

1 Describe the OSI model.?
2 What is the difference between a repeater, bridge, router?
relate this to the OSI model
3 Describe an Ethernet switch and where it fits into the OSI model.
What is a VLAN? What is an ELAN? What is the difference?
4 Relate FDDI/ATM/SONET to the OSI model.
5 Explain how to configure a host network interface (e.g. IP address, netmask, broadcast address)?
 6 Describe Ethernet packet contents: min./max. size, header.
 7 Describe TCP/IP and its protocols.
 8 Describe ATM and what are its current advantages and disadvantages.
Describe SONET
 9 What are the maximum distances for CAT5 cabling?
 10 Describe UDP and TCP and the differences between the two.
 11 What is your current IP address?
 12 Describe what a broadcast storm is.
 13 Describe what a runt, a giant, and a late collision are and what causes each of them.
 14 How do you distinguish a DNS problem from a network problem?
 15 Describe the Bandwidth Delay problem.
16 Describe the principle of multi-layer switching.
17 Describe the purpose and basic functionality of things like HSRP, VRRP etc.

Network Troubleshooting
1 Explain how traceroute, ping, and tcpdump work and what they are used for?
2 Describe a case where you have used these tools to troubleshoot.?
3 What is the last major networking problem you troubleshot and solved on your own in the last year?
4 What LAN analyzer tools are you familiar with and describe how you use them to troubleshoot and on what media and network types.

Routing 
1 Explain the contents of a routing table (default route, next hop, etc.)?
2 What routing protocols have you configured?
Describe the commands to set up a route.
What routing problems have you troubleshot?
3 How do you display a routing table on a Cisco? on a host?
4 How do you use a routing table and for what?
5 What is a route flap?
6 What is a metric?
7 When do you use BGP, IGRP, OSPF, Static Routes?

Network Security
1 What do you see as current networking security issues (e.g. NFS mounting, spoofing, one time passwords, etc.)?
2 Describe a routing filter and what it does.
3 Describe an access list and what it does.

Network Management
1 What is a network management system?
2 Describe how SNMP works.

Previous Work
1 Describe the working environment you are currently in, e.g. frequent interruptions, frequent priority shifting, team or individual.
2 What do you use to write documentation? Editor? Mail reader?
3 What platform (s) do you currently work on at your desk??
4 How do you manage multiple concurrent high level projects?
5 Describe a recent short term stressful situation and how you managed it.
6 How do you manage a long term demanding stressful work environment?
7 Have you worked in an assignment based environment, e.g. work request/trouble ticket system, and if so, describe that environment.

Programming
1 What applications have you written in C, JAVA, PERL, or other languages.

Network Statistics and Measurement
1 Describe what network statistics or measurement tools you are familiar with and how you have used them.

Wireless
1 Describe how 802.11b works and the advantages and disadvantages of using it.?
 2 Describe how WEP works and its strengths and weaknesses
 3 Describe what a VPN is and how it works.

VoIP
1 Describe how VoIP works.?
2 Describe methods of QoS.
3 How does to ToS bit work?

Project Management
1 Describe a long term, large scale project you managed.
2 What is your experience with scheduling and project management?
3 What computer packages have you used?
4 What tools have you used?
5 How many staff have you directly managed?

Training/Presentations
1 How would you train other engineers/technicians on network troubleshooting??
2 What is the last formal training you have had including seminars, tutorials, classes, etc.?
3 What conferences have you attended in the last two years?
4 What periodicals do you read on a regular basis?
5 What professional organizations do you belong to and participate in?

DWDM/transmission?
1 What is an EDFA? (Or, why do long haul fiber transmission systems use the 1530 1565 nM c band?)?
2 What is dispersion?
3 What is so good about Non Zero Dispersion Shifted Fiber (NZDSF)?
4 What is the difference between an amplifier and a regen site?
5 What does section, line, and path refer to in SONET??
6 How many bps does an OC 192 carry?

Other Potential Questions
1 Are you familiar with IPv6? If so, what are the major differences between IPv4 and IPv6?
2 What QoS mechanisms are you familiar with? Which have you implemented and to support what function or application?
3 What is your preferred method for creating and editing HTML files?
4 What authentication, authorization ad accounting (AAA) mechanisms are you familiar with? Which ones have you implemented??

* When it comes to facts, you must answer with facts. But when it comes to solution, you can create a solution base on your experience. It is same goes to your opinion, no wrong answer but your opinion must be supported by a good reason.