What Technical Questions To Ask During An Interview?

If you aren’t bringing someone up from the ranks, bring out some gear and create situations.  While it’s true most things can be learned by osmosis if they are a true tech, some hardware and software takes experience with them. IMHO. 

My mock interview with Marty Calhoun below...

Answer key: (No was reference material used to be fair to applicant)

Have you ever heard of IPVM? (Prove it.)

Marty sells Hik, Hik gets big loan, Marty laughs all the way to the bank.

What voltage does an Analog camera video signal travel?

Varies. Assuming you are actually measuring it, could be near 0v (black), up to 1v (white). Nominally referred to a 1v.

Who is Neil Councilman?

2 of the three designers of the common coaxial BNC connector

Why are 1080p Monitors not refereed to as 2k?

Because they don't have 2000 vertical lines. Follow-up question if answered correctly "So why are they not called 1k monitors then?"

What is an "I " frame of video?

The in-between frame of or baseline frame progressive video codecwhich progressive changes in the scene or p-frames, are added to, to create the full-frame

What is an SFP stick?

A common plug-in format, used often with higher-end switches to extend media formats, e.g. 10G/optical interfaces.

Explain the difference between Watts, Current and Voltage?

Watts is a unit of measure for power, power is the product of current and volts.

Working with Ethernet POE and assuming you have a 568B connection which pins provide Power to the device?

No different than 568A: Any. 1237 or 4578. Or all of them with newer high power standards.

Explain the difference in "Series and Parallel circuitry".

Series circuits increase resistance and decrease current with each leg, parallel circuits decrease resistance and increase current with each leg.

Please explain Class A, B & C as it relates to Networking.

Obsoleted 20th century terminology relating to subnetting, A is the largest domain with 65k hosts, C the smallest with 254. Supplanted by CIDR.

What are some of the differences in Multi-Mode fiber and Single Mode?

Multi-mode is cheaper, Single mode is higher performing and higher priced.

I think that the process that the tech uses to troubleshoot problems is more important than any specific familiarity with any equipment. Does he or she go about things methodically, or simply start pushing buttons and changing settings? What resources and tools does he or she use? Are the troubleshooting steps taken being taken documented as the tech goes along? 

I feel that the best way to determine the tech's process is create a few different types of troubleshooting scenarios and watch how they go about solving them.

When I was a very young man, I took on a contract to service some very complex industrial communications equipment to supplement my alarm business. The man who previously had the contract was a friend and mentor. To get me prepared, he would make me troubleshoot and repair actual equipment that he had deliberately introduced faults into. Every night, he would short out a diode or transistor or loosen a connection behind my back and then make me methodically find and fix the problem. He would then review the process that I used and offer his critiques. This went on for weeks.

When I finally went out in the field, I felt fully qualified to service the equipment and rarely encountered a problem that I couldn't solve. 

Jay, good question, thanks for asking it.

We have 50+ quizzes that you may want to scan through and see what questions you may want to pull from them to ask the tech.

One key question is how much you want to test them on the lines they have used vs the lines you use vs fundamental knowledge. If the tech being interviewed claims to have experience in exactly your lines, than I would think it makes sense to test them on that. However, you may learn more about what they really know (or don't know) by asking them questions on fundamentals (like what are the tradeoffs of adjusting shutter speed, compression, FoV width or what impact does upstream bandwidth have on video surveillance systems, etc.).

Is there a post missing? I got an email showing another post but its not here..?

But you are both right. I do not expect a tech to walk in knowing our exact products. But evaluating how they approach tasks, ask questions, is the key factor.

I have found I get the best information from two questions.  One of them is a scenario I make up that has to do with what their job role would be and ask how would you approach this scenario.  I could gauge how much management verse field work they have done as well as how they think about the specific job role.  If it is all ice cream and pony rides verse negative answers.  I would then ask them to explain a successful project/day and an unsuccessful project/day.  I feel you can gauge a lot from letting a potential new employee answer these questions. I would also recommend you have their manager listen and see if they are a fit.

Also I advise you to seek out legal advice as there may be Dept. of Labor laws regarding interview questions.  I was told by a regulatory agency that all interview questions have to be 100% the same.  I answered well I have a conversation with the human I am speaking with so I really do not know where it is going to go.  They did not like that answer but it was fun to say it!  

You can learn a lot about a tech by asking "what is your favorite camera/VMS/alarm/access control system, and why?"