Entry-level Interview Questions

[icecream-guy]

Ask the noob what a nibble is, if he don't know, ask the noob what a nibble and 4 bits is?  if he still don't know, end the interview.
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[Otanx]

Ask the noob what a nibble is, if he don't know, ask the noob what a nibble and 4 bits is?  if he still don't know, end the interview.
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Word.

-Otanx

[deanwebb]

Back to my original intent... more questions you would want to ask someone that was coming in to support/assist you in a junior role. Not just rack-n-stack, run-that-script stuff, but a role that requires some troubleshooting-type intuition.

Definitely ask about ARP and if the guy says, "It's a protocol... for... resolving... uh... addresses?", this is not your troubleshooter.

For a firewall guy, I like to ask, "A customer requests that you permit traffic from host A to host B on port C. You create the rule and test that traffic can go from A to B on port C. The customer, however, says that his application is not working properly. What should you do to help the customer?"

The best answers start with, "I would ask the customer about..."

[icecream-guy]

For a firewall guy, I like to ask, "A customer requests that you permit traffic from host A to host B on port C. You create the rule and test that traffic can go from A to B on port C. The customer, however, says that his application is not working properly. What should you do to help the customer?"

The best answers start with, "I would ask the customer about..."

1. is the application listening on the port?
2. is there a host based firewall enabled on the server?
3. is the server routing returning traffic out the correct interface?

we always have to ask these 3 questions.

[NetworkGroover]

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)

Haha - that would be an impressive start to the question, but yeah focused on the network side and not from the PC side.

TCP handshake, HTTP Get, 200 OK, ARP, how the PC determines if the destination is local or remote, how the dst MAC is written and if it changes and where ... it can lead into a whole slew of basic networking topics.

[deanwebb]

For a firewall guy, I like to ask, "A customer requests that you permit traffic from host A to host B on port C. You create the rule and test that traffic can go from A to B on port C. The customer, however, says that his application is not working properly. What should you do to help the customer?"

The best answers start with, "I would ask the customer about..."

1. is the application listening on the port?
2. is there a host based firewall enabled on the server?
3. is the server routing returning traffic out the correct interface?

we always have to ask these 3 questions.

I also like to ask if there are other ports required by the vendor that may or may not be documented...