Entry-level Interview Questions

[deanwebb]

Had an incident today in which I asked, "What are some problems that could arise from having a remote site deciding to use an IP address range without coordinating with the central IP management team?" and the interviewee started to try to look up the answer. I could hear the mouse clicks and pages turning all through the awkward silence. The interviewee had no answer, in spite of his CCNA and CCNP-Switch certs listed on his resume.

I expect an interviewee to know the answer to the above question without feeling a need to look up the answer. What are some other questions that entry-level people should know the answers to, without hesitation?

[dlots]

I have never given an interview, always been on the receiving side.

I will say I wish people would stop asking sub-netting questions though, along with what ports = what protocol, these are what google is for.

ARP is always a good question.
tracert is good

[NetworkGroover]

Had an incident today in which I asked, "What are some problems that could arise from having a remote site deciding to use an IP address range without coordinating with the central IP management team?" and the interviewee started to try to look up the answer. I could hear the mouse clicks and pages turning all through the awkward silence. The interviewee had no answer, in spite of his CCNA and CCNP-Switch certs listed on his resume.

I expect an interviewee to know the answer to the above question without feeling a need to look up the answer. What are some other questions that entry-level people should know the answers to, without hesitation?

Entry level people handle IP allocation/design?

I would have answered, "That should never happen as an entry-level position.  The IP allocation and design schema should already be pre-planned and as an entry-level engineer I should be provided with what range to use - maybe even down to what specific IP addresses are to be used where."

[NetworkGroover]

I have never given an interview, always been on the receiving side.

I will say I wish people would stop asking sub-netting questions though, along with what ports = what protocol, these are what google is for.

ARP is always a good question.
tracert is good

Hmmmm I guess in response to this and Dean's post, "entry-level" can mean different things depending on the size of company you work for... in a large organization, I wouldn't expect a lot from an entry-level dude except for how to console/login into a device, follow instructions, and be able to verify correct results (though I'd probably expect even this to be handed to him along with the config if the senior engineer is a good dude). If things go wrong, know what data to collect (make no changes him/herself) and escalate to the appropriate resource.  Anything more than that is great, but he better not be using that knowledge to take his/her own action on my production network without my permission.  He wouldn't be designing anything either, so knowing subnetting is ok but not that important to me outside of being able to troubleshoot someone setting an incorrect default gateway.  Agree - tracerouting, knowing ARP, general protocol knowledge and more importantly, how to research how a protocol should work - these are all good because it helps him interpret an issue and collect data - especially analysis in Wireshark for snarky application stuff.  Again though, entry-level actual modification of network configuration should be extremely limited in my opinion.

EDIT - Hell, in a large organization, config changes should be pushed or automated and automatically verified anyway.. xD

[deanwebb]

Had an incident today in which I asked, "What are some problems that could arise from having a remote site deciding to use an IP address range without coordinating with the central IP management team?" and the interviewee started to try to look up the answer. I could hear the mouse clicks and pages turning all through the awkward silence. The interviewee had no answer, in spite of his CCNA and CCNP-Switch certs listed on his resume.

I expect an interviewee to know the answer to the above question without feeling a need to look up the answer. What are some other questions that entry-level people should know the answers to, without hesitation?

Entry level people handle IP allocation/design?

I would have answered, "That should never happen as an entry-level position.  The IP allocation and design schema should already be pre-planned and as an entry-level engineer I should be provided with what range to use - maybe even down to what specific IP addresses are to be used where."

Even so, entry-level guys should be able to see dangers inherent in certain situations. And, to be sure, it may not be Mr. or Ms. Entry-level that enters the rogue IP range, but is the person that discovers it. If I got a person that just shrugs and figures, oh well, somebody else's IP address conflict sitch, then I'm the guy on the left and he's the guy on the right:

[deanwebb]

EDIT - Hell, in a large organization, config changes should be pushed or automated and automatically verified anyway.. xD

Every time we try to do an automated push, there's always a story time for the 20% of the gear that won't accept it and which needs manual config modification.

[SofaKing]

I like the ARP and tracert questions suggested by dlots

I would start off with asking who they voted for

Maybe ask the difference between TCP and UDP.  Was there something in the job description that said the applicant must have x, y, and z skills?  If the applicant was serious about the job they would have at least reviewed those skills.  I would also ask something you know they wouldn't know just to see how they respond.  Lie, get back to you, surprise you by knowing the answer... either way you'll learn a little something about the person.  If they talk out their a$$ I would probably not want that person.

[icecream-guy]

liks sofaking says let the job description guide you.   other than knowing the difference between a router and a switch, or different layers of the OSI.
You really got to stick with the fundamentals for the noobs,  if they have a clue about fundamentals, that'd up level them for consideration of a face to face interview.

[deanwebb]

In security, I like to ask non-vendor specific theory types of questions. Most likely, the candidate I'm interviewing hasn't worked with the vendor we're using for X, but he has worked with X before... maybe...

If he's never done security, then at least he better know routing and switching to the level presented on the resume. I see a CCNA, I'll ask CCNA questions. I see a CCNP, then homestar better know his layer 2 from his layer 3.

[jason.copas]

Had an incident today in which I asked, "What are some problems that could arise from having a remote site deciding to use an IP address range without coordinating with the central IP management team?" and the interviewee started to try to look up the answer. I could hear the mouse clicks and pages turning all through the awkward silence. The interviewee had no answer, in spite of his CCNA and CCNP-Switch certs listed on his resume.

I expect an interviewee to know the answer to the above question without feeling a need to look up the answer. What are some other questions that entry-level people should know the answers to, without hesitation?

I listen to data center interviews a lot because our data center guy is on their hiring team.  The number of people I hear miss the questions "what does DNS do" and "what does DHCP do" is staggering.  At least 50% miss one or both...

Access vs Trunk port makes a good question.  They should be able to explain dot1q tags, but a lot can't.

Sent from my Nexus 6 using Tapatalk

[NetworkGroover]

Had an incident today in which I asked, "What are some problems that could arise from having a remote site deciding to use an IP address range without coordinating with the central IP management team?" and the interviewee started to try to look up the answer. I could hear the mouse clicks and pages turning all through the awkward silence. The interviewee had no answer, in spite of his CCNA and CCNP-Switch certs listed on his resume.

I expect an interviewee to know the answer to the above question without feeling a need to look up the answer. What are some other questions that entry-level people should know the answers to, without hesitation?

Entry level people handle IP allocation/design?

I would have answered, "That should never happen as an entry-level position.  The IP allocation and design schema should already be pre-planned and as an entry-level engineer I should be provided with what range to use - maybe even down to what specific IP addresses are to be used where."

Even so, entry-level guys should be able to see dangers inherent in certain situations. And, to be sure, it may not be Mr. or Ms. Entry-level that enters the rogue IP range, but is the person that discovers it. If I got a person that just shrugs and figures, oh well, somebody else's IP address conflict sitch, then I'm the guy on the left and he's the guy on the right:

Ehhhh I guess it depends where you're at, again.  If it were me, I'd take that as my own fault for not properly planning and controlling IP usage in my own environment. Easy for me to say though.

[NetworkGroover]

EDIT - Hell, in a large organization, config changes should be pushed or automated and automatically verified anyway.. xD

Every time we try to do an automated push, there's always a story time for the 20% of the gear that won't accept it and which needs manual config modification.

Is that a problem with the tools or a problem with your org?

[NetworkGroover]

I like the ARP and tracert questions suggested by dlots

I would start off with asking who they voted for

Maybe ask the difference between TCP and UDP.  Was there something in the job description that said the applicant must have x, y, and z skills?  If the applicant was serious about the job they would have at least reviewed those skills.  I would also ask something you know they wouldn't know just to see how they respond.  Lie, get back to you, surprise you by knowing the answer... either way you'll learn a little something about the person.  If they talk out their a$$ I would probably not want that person.

Oh good lord, in this day and age getting the "who you voted for" out of the way could actually sadly be a pretty quick indicator on if you're going to fit in or not.... lol.

I've also always liked the, "Walk me through what happens when a host machine requests a webpage assuming all caches/tables on all devices in the path are empty."  question.  That's the type of question where it's too much to just memorize port numbers , and covers many concepts that you can talk about and see if they have an overall understanding of what's going on.

[icecream-guy]

I've also always liked the, "Walk me through what happens when a host machine requests a webpage assuming all caches/tables on all devices in the path are empty."  question. 

can I assume the PC is booted and in a somewhat sedentary state, that I'm logged in with the web browser open?


Boy, that could end up being a PHD dissertation, if one gets down into the nitty gritty details.

I press a key, which invokes an interrupt to the CPU, the interrupt travels along the CPU bus to the CPU. the CPU processes the information, information is transferred to the video contoller, and processed by the GPU, eventually a letter pops up into the navigation bar on the screen. I do this several more times.... and hit enter.....

(or something like that, I've not worked on PC's in a number of years and probably messed up a few steps, forget how the process actually works)

[deanwebb]

Ehhhh I guess it depends where you're at, again.  If it were me, I'd take that as my own fault for not properly planning and controlling IP usage in my own environment. Easy for me to say though.

Any global megacorp is going to have rogue/shadow IT where locals simply don't know who to talk to about their IT needs and just do it themselves. They don't get found out until that IP address conflict between their wireless range and one of our datacenter ranges becomes apparent. We've got 15K+ ranges that we know about and manage in our DDI. I do NAC, so I find the ranges that are duplicates of those or that are not in DDI.

And for the lack of automation... again, any global megacorp does M&A stuff and those are always a headache, getting one IT system to work with another built along different lines. Compromises happen and that leads to story time when someone asks why is it we can't use Prime to push configs to our sites in Elbonia?