What kind of networking questions do you ask an candidate in an interview?

I'm in an interesting issue. My manager has been having me interview new potential network engineer candidates and I've been using what I think are easy questions to screen their technical skills. Without fail, people with 10-15 years of "senior network engineer" experience can't answer 9/10 of my questions.

I ask some pretty basic EASY stuff:
"How do you configure an SVI on a multilayer switch?" (Best response - "You create a subinterface...")
"How do you enable routing on a multilayer switch?"
"You are viewing the ingress traffic on a multilayer switch by means of a SPAN port. Just looking at the packets going in, how can you tell whether the packets are going to L2 or L3 switched?"
"Oh, I see you have experience with (whatever routing protocol listed on their resume). How would you configure that on a router?"
"How do you configure rapid spanning tree?"
"Give me the general idea of STP?"
"What is a VLAN and how do you create one?"
"How do you configure VTP?"

Without fail, people with years and years of experience get 9/10 questions wrong and when I mean "wrong," I mean not even REMOTELY right.

What is the experience of other engineers out there? What kind of questions do you ask?
Am I being too mean or just running into a lot of slow people?

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Comments

wes allen

So, you all type up all your configs from scratch, live on the cli? Most of what I do is upgrades, so I **** the current config to a txt file with teraterm edit it as needed in notepad++, then save as a new file, so I have the old one to use for reference. Cut and paste the commands from new file into cli, and verify as I go. When i am done, i have old and new configs saved, along with another txt doc with other info that might be useful

Your questions are exam quiz types, which is fine and all, but asking about what tools someone uses and how they use them might give you more insight into what they actually do.

GOZCU

3 months ago my interview questions;

http://www.techexams.net/forums/jobs-degrees/84734-had-technical-interview-feeling-myself-so-stupid.html

Now i see how easy questions were them. Any experience at the interview is worth to have it. You learn from your mistakes very fast.

Now i doubled maybe tripled my knowledge. Ah forgot to say, yeah i got the job after that interview( after actually 3 additional interview). I even got promotion 1 week ago.

sratakhin

This topic made my day

Although I'm not sure what's funnier - this or the month old topic about hiring a professional who did a Webex session with someone in India

Zartanasaurus

Iristheangel wrote: »

"You are viewing the ingress traffic on a multilayer switch by means of a SPAN port. Just looking at the packets going in, how can you tell whether the packets are going to L2 or L3 switched?"

What do you consider the "right" answer here?

Iristheangel

@Zartan - there can be several right answers. The destination MAC address, the source and destination subnet, etc. I like to see how they approach the question and if they understand how it generally works

Essendon

Excellent thread!

We recently interviewed for a mid-senior level sys admin position and the one of the tasks was to join a laptop the domain. The laptop appeared to have a network cable plugged in (it actually wasnt in the whole way!). I interviewed 6 people and gave them the DNS server's IP address and credentials to join to the domain. None of them thought of the network cable, just sat there scratching their heads.

Me - Perhaps check layer 1
Them - Ping the DNS server and - O I cant ping the server
Me - Right, so what do you think the issue is?
Them - Your DNS server is turned off.
Me- Ok, anything else you could think of?
Them - Windows firewall!! Yes, it's got to be the firewall
Me - Go ahead and check Windows firewall.
Them - Damn, it's off already.
Me - Lemme put this question another way, if you are trying to iron your shirt but the iron doesnt seem to have any life in it, what could be the problem?
Them - it isnt connected. Light!! Red-faced!

It's the thought process that I interview about really. I'd engage them in technical discussions too, just talk about a topic and see what their depth is.

NetworkVeteran

Zartanasaurus wrote: »

What do you consider the "right" answer here?

I'm not sure her question lends itself to a single right answer. It's the sort you could give an answer, she could provide some clarification, you could provide another answer, etc. This is a good opportunity to demonstrate your understanding.

1) You could check for ARP requests. These indicate IP destinations not on the local subnet, requiring L3 switching (now or later).

2) You could check for the same MAC address being used by many IP addresses. That's almost certainly the default gateway's MAC address, and would indicate some L3 switching was necessary--probably being done by this very switch.

3) Often the src/dst IP alone makes it obvious if the two are on different networks and L3 switching is necessary (now or later).

By interpreting "the packets going in" to mean all interfaces rather than just one--the question left that ambiguous--you could provide a much more comprehensive answer, as long as she didn't call you on "cheating".

chmod

When I do interviews i never focus on "how to" type of question i focus on his foundation if has good foundation that is what i actually care about, in you understand how things works you can just read a manual and refresh your CLI knowledge is all about understanding the technologies more than knowing a lot of commands you can even memorize them but not understand them, so how you design or troubleshoot something you don't understand deeply.

I love the blackboard so i enjoy asking them: Can you show me how this works, explain to me the process of....., let me picture the following scenario and tell me what would do in this case or show the mistakes, the i ask more questions based on what they respond and engage them into technical discussion but the blackboard is my favorite part it is easy to b/s an answer but to prove it with real life examples is different etc etc etc

Iristheangel

Chmod - Great answer and I agree. I've been in those interviews before and they're really great for practicality.

Iristheangel

wes allen wrote: »

So, you all type up all your configs from scratch, live on the cli? Most of what I do is upgrades, so I **** the current config to a txt file with teraterm edit it as needed in notepad++, then save as a new file, so I have the old one to use for reference. Cut and paste the commands from new file into cli, and verify as I go. When i am done, i have old and new configs saved, along with another txt doc with other info that might be useful

Your questions are exam quiz types, which is fine and all, but asking about what tools someone uses and how they use them might give you more insight into what they actually do.

No, I don't always write things out in the CLI and will prepare in Notepad when I can. But I also know what each command I use does and generally how to troubleshoot it. Asking someone what kind of USB serial adapter or terminal program they use is the equivalent of "what kind of browser do you use?" I am sure everyone has an opinion but the reality is that it's irrelevant to me whether they use regular Notepad vs Notepad+ or SecureCT vs Putty if they do not understand the underlying technology. The reality is that we're paying the person we hire a LOT of money to know what they're doing, not because of what programs they prefer. Is the answer to what kind of tools they use going to tip the scales in regards to whether I recommend them to be hired or not? Nope. Not in the least bit.

wes allen

I just think you can easily weed out people that only uses gns3/packet tracer/etc by asking questions about their workflow. You said you all hired a CCNP who had trouble with putty, so if you would have asked more about what tools he uses on a daily basis, you might have found out more about his skill set. Ask a programmer what they like to use to write code, and people that answer vim probably know a bit about what they are doing. As will someone that likes sublime, compared to someone that is a big GUI person. When I am working, I live in teraterm pro, notepad++, google, and a adobe reader. Those are my tools, which, are useless if I don't also know how to apply them to do "stuff". I hate terminal, and putty seemed kinda meh last time I used it. I should just suck it up and buy secureCRT, I guess, but Teraterm works well enough.

Again, tech questions are a big part of interviews, as specific config ones, or as general "lets talk about x", but learning about someones workflow can tell you alot as well. If you ask "how do you document your configs" and they give you a blank look, odds are they don't do much actual configuring. Same with USB adapters, some suck, and if you use one all day, you will know that, vs if you only know GNS3.

Mrock4

I think I see where you're going wes- but it's a lot easier to **** an interview where you're asked "how do you document your configs?" as opposed to "how do you configure EIGRP?" - even someone who has never documented their configs could quite quickly respond with some generic workflow such as "I copy and paste them into notepad, and save them with dates/other descriptive info/version numbers." Might not be the optimal solution, but that's still a form of documentation. Alternately, that same person couldn't come up with a BS answer for how you configure EIGRP. Well, they could, but since there is only a limited number of answers, it'd be easy to weed them out.

It's just my $.02, but I think there's room in ONE technical interview for variations of these techniques- speaking of workflows, technical questions, scenarios, etc. Some of my favorite questions are leadership/team-based questions. Granted, that isn't the ONLY part of my interviews, and that's not strictly for a technical interview, but more for general candidate screening. Truthfully, I think incorporating multiple methods would probably ultimately result in better candidate selection.

wes allen

Mrock4 - I totally agree that you can BS some workflow questions easier then others, just like you can pass CCNP and answer EIGRP config questions and not know how to connect to a router with a serial cable. So, asking questions about workflow, even simple things, can help weed out some of the people that passed the test, but still don't know what they are doing. And, it might let people that may be a bit dated on some of the specific tech show that they know networking and can learn the cmds they need pretty easy. More then anything, it lets you have a conversation with someone about how they work.

Xyro

Essendon wrote: »

It's the thought process that I interview about really.

This is exactly what you have to aim for. I completely agree.

Success101

And to think I can't even get an interview...

Xyro

Success101 wrote: »

And to think I can't even get an interview...

Ironic, isn't it. Keep trying though!

jibbajabba

I hate quizzes like that .. For example - I got 3 VMware VCPs and one guy quizzed me VCP3 style - purely minimum and maximum .. .I don't bloody know (anymore) - get me a broken vSphere infrastructure and I fix it but none of that nonsense haha ..

Seriously though - if you need to hire a network engineer who knows his stuff - why even bother quizzing ? Why not setup a bunch of switches and routers - setup a scenario - ask the guy to bring a laptop and his favorite serial adapter and give him tasks to do.

At the end the job is hands-on so I'd test hands-on ... I guess the problem is to sort out the lemons before inviting in. I get it ... But I am sure you get a good idea if he talks rubbish by just quizzing what he has done and pick on an example. When I apply for jobs I do get the random quiz over the phone, but sometimes I have a very technical guy at the other end. When I say "I created a multi-site Exchange 2010 infrastrucutre" - that guy asked me how I done it, why I done it the way I did etc. That way you usually can call BS already very early.

So if someone tells you he configured STP - asked him how he did it.

I ONCE had to help to interview someone for a VMware related role and I was the most senior for VMware ... I asked a few basic questions over the phone (What is vmotion / drs / storage drs and so on). When the guy came in, I had a cluster setup on my laptop (nested cluster using VMware Workstation).

The cluster had "issues" - Vmotion was not working and other day-2-day issues you may face. I gave him the laptop and asked him to fix it or at least tell me what he thinks is wrong with it - I explained what isn't quite working and let them do the rest

I had someone who didn't even know that he needs the vSphere client to connect to the vCenter ... then another guy said he couldn't do it as this is not a real scenario (err what) ..

So yea - I prefer scenario based interviews

Essendon wrote: »

Excellent thread!

We recently interviewed for a mid-senior level sys admin position and the one of the tasks was to join a laptop the domain. The laptop appeared to have a network cable plugged in (it actually wasnt in the whole way!). I interviewed 6 people and gave them the DNS server's IP address and credentials to join to the domain. None of them thought of the network cable, just sat there scratching their heads.

Me - Perhaps check layer 1
Them - Ping the DNS server and - O I cant ping the server
Me - Right, so what do you think the issue is?
Them - Your DNS server is turned off.
Me- Ok, anything else you could think of?
Them - Windows firewall!! Yes, it's got to be the firewall
Me - Go ahead and check Windows firewall.
Them - Damn, it's off already.
Me - Lemme put this question another way, if you are trying to iron your shirt but the iron doesnt seem to have any life in it, what could be the problem?
Them - it isnt connected. Light!! Red-faced!

It's the thought process that I interview about really. I'd engage them in technical discussions too, just talk about a topic and see what their depth is.

To be fair though lol - the more senior you get, the more facepalms you are getting like that - I remember a few people, including IT manager scratching their heads about a 2003 server which seemed to have a bust OS for no reason and they NEEDED to get access to it .. Took me two seconds to notice that they had a floppy disk in there which the system tried to boot from.

Once you are "in the field" for years - you sometimes forget the easy things and just think too complicated.

Another issue I remember with similar facepalm reaction was a VPN server which seemed to be bust ... hardware was swapped, server was even P2Ved and it just wasn't working right .. after half a night we found out that the firewall was running a high CPU and dropped packets

chmod

This thread reminds of an interview to an 8 yrs of expence sys admin a few years ago: I asked him, please show me what happens when you type google.com in your browser, i want you to show me in the blackboard how a dns works please provide details(port#, protocol etc) and how a zone transfer works also provide details.

MCSA and he said men i don't remember. Funny how many techies out there don't even know the most basic stuff.

PurpleIT

First, let me say as someone that will be sending out resumes in the next 6 weeks or so, I love this topic. The idea of seeing what type of questions I might expect along with the feedback from the members here gets me really excited. Any feedback you (or anyone else reading this) might have would be greatly appreciated.

For me, and this may show my shortcomings more than anything else, the issue isn't so much that I wouldn't know these answers, but the questions are a little awkward. To me, you don't configure the SVI, the SVI simply is. If you were to ask how to configure inter-vlan routing on an L3 switch (not just enabling the routing) I would have no problem saying, "create the vlans on the switch, assign them IPs and oh, make sure IP routing is enabled".

For some of your questions, I think they are begging for clarification (which is a good thing IMHO because it is a chance to show general knowledge as opposed to just answering a direct question), the one that comes to mind is "how do you configure RSTP". By asking for clarification, "do you mean simply enabling it or something such as configuring the root bridge" a person shows that they know more than a command, they know about a potential issue with the technology.

Given the scenario you posted with the employee who only lasted a short time I know I could do that job; now I just need to find such a beast with similar pay in Denver.

webgeek

Essendon wrote: »

Excellent thread!

We recently interviewed for a mid-senior level sys admin position and the one of the tasks was to join a laptop the domain. The laptop appeared to have a network cable plugged in (it actually wasnt in the whole way!). I interviewed 6 people and gave them the DNS server's IP address and credentials to join to the domain. None of them thought of the network cable, just sat there scratching their heads.

Me - Perhaps check layer 1
Them - Ping the DNS server and - O I cant ping the server
Me - Right, so what do you think the issue is?
Them - Your DNS server is turned off.
Me- Ok, anything else you could think of?
Them - Windows firewall!! Yes, it's got to be the firewall
Me - Go ahead and check Windows firewall.
Them - Damn, it's off already.
Me - Lemme put this question another way, if you are trying to iron your shirt but the iron doesnt seem to have any life in it, what could be the problem?
Them - it isnt connected. Light!! Red-faced!

It's the thought process that I interview about really. I'd engage them in technical discussions too, just talk about a topic and see what their depth is.

Loved this!

andy4tech

I believe as a CCNA you should be able to answer 9 out of the 10 questions with the exception of SPAN port question.

Kelkin

I love these posts.. It shows just how human we the network engineers are..

I consider myself a pretty good network engineer but I have the hardest time in interviews articulating responses. Its like there's a disconnect between my Brain and mouth

Nyblizzard

I don't have any Cisco certifications, but am I to believe that someone with a CCNA and no job experience is able to answer most of these questions?

broli720

I've never been in this position but from other threads I've read it's usually a good idea to make it open ended. Have them illustrate a network that they've worked on. This allows both of you to talk in a sort of informal way to make them comfortable. Depending on the type of diagram they give you, you can ask a series of question to see where they are technically.

In my last role my supervisor did this when I interviewed for the position. A simple PAST diagram turned into a 30 minute interview

Zartanasaurus

Iristheangel wrote: »

We pay very very very well. Above six figures

Well I was planning on moving soon and those questions are pretty easy so...

Iristheangel

LoL. Amusingly enough, my questions are the hardest ones. I'm the "bad cop" in interviews. Hit me up on PM and I can arrange an interview if you end up in California

Zartanasaurus

I can't find the article right now with Google for some reason, but there was a good article over at Etherealmind about how he conducts interviews and the types of questions he likes to ask as well as the ones he doesn't like to ask.

The main one he liked was essentially "draw your previous network on the whiteboard" and he can learn a lot about what the candidate knew just from that and tailor his questions from there.

I'm stunned that simple questions like "how do you configure an SVI" are the tough questions and the barrier to a 6 figure salary.

Mrock4

Nyblizzard wrote: »

I don't have any Cisco certifications, but am I to believe that someone with a CCNA and no job experience is able to answer most of these questions?

She was interviewing an individual who claimed to have years of experience..it wasn't a CCNA with no job experience.

Iristheangel

@Zartan - It really depends on the company. I interviewed with a fairly well-known networking company in San Jose for 8 hours straight and I got drilled every which way from configs to design to logic puzzles. I was later offered the position but turned it down because a) they're not a market leader in networking equipment and I would be incredibly siloed in my experience there and b) they offered only $70K/year for the position of network engineer.

Based on what I've seen of you on these forums, Z, you would ace any interview we would throw at you and I would go as far to say that I would probably highly recommend you as far as technical skill

I will give them credit though - that interview was INTENSE but fun. I've stolen some questions from that interview and used them in interviews I've been in like the SPAN question or drawing out a network with a switch, router, computer, DNS server and access to the internet and saying "You just booted up a new computer and new switch. Explain in detail what happens if you want to pull up a browser and navigate to Google. Bear in mind, this switch is just started up and so is the computer. I'll make them walk through ARP, DNS, routing, etc

Zartanasaurus

Mrock4 wrote: »

She was interviewing an individual who claimed to have years of experience..it wasn't a CCNA with no job experience.

I would expect a CCNA with no job experience to get in the ballpark of answering the first and last 4 questions decently. Basic Layer 2 stuff there which is covered in that track. The SPAN question should be answerable, but might throw the candidate off by the use of the term so they would be thinking there's some secret magic going in that they haven't experienced yet. I agree with NV (I think it was) that said the question could be more generalized to just packet capture.

I'm currently training my replacement at work as well as preparing them for the CCNA, and I go over these types of "interview question scenarios" with them any time I lecture on a particular topic. I constantly stress the importance of being able to use the proper technical terms. I think word choice is very important because we judge intelligence and knowledge based on speech and writing.

drawing out a network with a switch, router, computer, DNS server and access to the internet and saying "You just booted up a new computer and new switch. Explain in detail what happens if you want to pull up a browser and navigate to Google. Bear in mind, this switch is just started up and so is the computer. I'll make them walk through ARP, DNS, routing, etc

I think this is a great question. I did this same thing with my trainee except it was ping. I went over it myself, then expected him to be able to do the same thing at a later date, complete with packet encapsulations. IP protocol #s and ethertype codes. I made sure to include trunking links between switches as well as multiple VLANs to make sure they got the broadcast domains and dot1q tagging as part of the process.