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[OT] Help with interview questions

Hi,

Firstly I'd like to apologise for posting to this forum, as I was unsure which one to post to.

I've just been told that I can hire another network administrator, my problem is that I've never done or taken a network administration/engineering interview before, so I'm at a loss as to what to ask for apart from simple questions like:

1. How does tcp connection work

2. How would you setup a bgp connection

3. What is the difference between sparse and dense mode multicast?


Personally I can't see what value the above will give apart from screening initial applicants out, after that process I'll need some info on how to interview potential applicants and test their network and problem solving abilities.

Can you please give me typical scenarios or questions as I assume people here have been through this process.

Many thanks for your patience and help.

Dan

3 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Blue

Re: [OT] Help with interview questions

dan_track wrote:

Jon,

Many many thanks for that insight. I'll try and think of some scenarios based around ospf, eigrp,bgp,nat,vpn.

If someone has some scenarios at hand that can share I'd appreciate it.

Thanks

Dan

Dan

Do you have access to a lab or some equipment that they could use ?

Also, what level are you expecting this person to be at ie. CCNA/CCNP etc.

Jon

Re: [OT] Help with interview questions

Dan,

An alternative approach is to ask the candidate to draw on a whiteboard a network that they have supported or designed.

You can then ask a wide range of questions to test various areas of their knowledge. You can also to choose to focus on any weaknesses in their knowledge that their presentation may reveal.

For example:

- What security measures did you implement?

-  What tools do you use to support the network?

- How does  redundancy work in your network?

- What happens if device X or Y fails?

- Where are the bandwidth bottlenecks?

- How would you  introduce a new routing protocol into the network?

- What is your  QoS policy?

It also is also a good test of the candidates "soft" skills:

- Presentation skills

- Ability to sell the merits of a design to a technical audience.

- Tests their ability to think on their feet.

- Tests the candidate's ability to perform under pressure.

Cisco will donate $1 to  the Red Cross Haiti fund for every  rated post!

https://supportforums.cisco.com/docs/DOC-8727

Hall of Fame Super Blue

Re: [OT] Help with interview questions

Dan

Sean's suggestion is a very good one (+5) because it will give you an idea of just how much experience and understanding they had at their previous company. I have interviewed CCNPs before and they can vary greatly in ability so you do need to drill down into their experience eg.

one CCNP i interviewed told me he was responsible for the whole MPLS network. After some questions about MPLS it became clear that in actual fact all he did was phone up the ISP to ask for a new circuit every now and then. By using Sean's example you should get an understanding of how much they actually know.

Other than that, use your own knowledge to set the questions ie. don't go off scouring through books to find an obscure example because that won't really tell you anything about them.

So for example with BGP you could simply present a configuration of 2 EBGP peers peering on their loopback addresses but without the ebgp-multihop command and ask why they are not peering successfully.

VPN, you could show a config for 2 peers that isn't working and make the crypto map acls mismatch for either side

etc..

Jon

8 REPLIES
Hall of Fame Super Blue

Re: [OT] Help with interview questions

Dan

Firstly, make sure that the questions you ask are focussed on what the person will actually be doing ie. there is no point in asking about MPLS if they are not going to be using it.

Asking concept questions rather than specific ones is a better approach and your suggested questions are along those lines. It's revealing to see how much detail and understand a person knows.

One question i like to use is to ask them to explain how host1 on subnetA talks to host2 on subnetB assuming host1 already has the IP address of host2, arp tables are empty and you are using ethernet.  What you are looking for here are the following steps -

1) host1 has to work out whether host2 is on the same subnet or not - how does it do this

2) when host1 realises it is on a different subnet what does it then do - ie. looks for default-gateway.

3) host1 arps out for default-gateway mac-address

4) host1 sends packet to default-gateway ( a router or L3 switch)

etc....

You get to see if they have a good understanding of how traffic is routed, how route lookups work, how L2 ethernet works etc..

Just as important as their knowledge is how they find a solution when they don't have the knowledge ie. what tools do they use to find answers. If they can show they have a good approach to this then you can be comfortable they won't need to be spoonfed every time they come across something new.

I suggest drawing up a list of things they must know for the job and then directing the questions towards those subjects.

Jon

New Member

Re: [OT] Help with interview questions

Jon,

Many many thanks for that insight. I'll try and think of some scenarios based around ospf, eigrp,bgp,nat,vpn.

If someone has some scenarios at hand that can share I'd appreciate it.

Thanks

Dan

Hall of Fame Super Blue

Re: [OT] Help with interview questions

dan_track wrote:

Jon,

Many many thanks for that insight. I'll try and think of some scenarios based around ospf, eigrp,bgp,nat,vpn.

If someone has some scenarios at hand that can share I'd appreciate it.

Thanks

Dan

Dan

Do you have access to a lab or some equipment that they could use ?

Also, what level are you expecting this person to be at ie. CCNA/CCNP etc.

Jon

New Member

Re: [OT] Help with interview questions

Hi Jon,

I'm expecting them to be at CCNP level.

Thanks

Dan

Hall of Fame Super Blue

Re: [OT] Help with interview questions

Dan

Sean's suggestion is a very good one (+5) because it will give you an idea of just how much experience and understanding they had at their previous company. I have interviewed CCNPs before and they can vary greatly in ability so you do need to drill down into their experience eg.

one CCNP i interviewed told me he was responsible for the whole MPLS network. After some questions about MPLS it became clear that in actual fact all he did was phone up the ISP to ask for a new circuit every now and then. By using Sean's example you should get an understanding of how much they actually know.

Other than that, use your own knowledge to set the questions ie. don't go off scouring through books to find an obscure example because that won't really tell you anything about them.

So for example with BGP you could simply present a configuration of 2 EBGP peers peering on their loopback addresses but without the ebgp-multihop command and ask why they are not peering successfully.

VPN, you could show a config for 2 peers that isn't working and make the crypto map acls mismatch for either side

etc..

Jon

New Member

Re: [OT] Help with interview questions

Hi All,

I very much appreciate this advise, it's been very valuable and has helped me to focus on my task.

Once again thanks for your help.

Dan

Re: [OT] Help with interview questions

Jon,

Thanks for the kind words and the rating.

Dan,

The other advantage of this interview technique is that it puts the candidate off balance from the start and gets them out of their comfort zone. This allows you to judge how they react to new situations.

Most candidates would be expecting a traditional interview where you discuss their CV and then they are asked a few set piece questions from a Cisco Press book.

The disadvantage of this technique is deciding upon a fair and equitable rating for each candidate after the interview since it can be so wide ranging.

A few years ago I was told about a person applying for a position claiming to be a network engineer. However after using some of the techniques discussed above it was found that all he did was assign IP addresses to servers and PCs from a spreadsheet.

Thanks

Sean

Re: [OT] Help with interview questions

Dan,

An alternative approach is to ask the candidate to draw on a whiteboard a network that they have supported or designed.

You can then ask a wide range of questions to test various areas of their knowledge. You can also to choose to focus on any weaknesses in their knowledge that their presentation may reveal.

For example:

- What security measures did you implement?

-  What tools do you use to support the network?

- How does  redundancy work in your network?

- What happens if device X or Y fails?

- Where are the bandwidth bottlenecks?

- How would you  introduce a new routing protocol into the network?

- What is your  QoS policy?

It also is also a good test of the candidates "soft" skills:

- Presentation skills

- Ability to sell the merits of a design to a technical audience.

- Tests their ability to think on their feet.

- Tests the candidate's ability to perform under pressure.

Cisco will donate $1 to  the Red Cross Haiti fund for every  rated post!

https://supportforums.cisco.com/docs/DOC-8727

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