Users at a branch office report that video calls are choppy every afternoon. How do you find the cause?

What the interviewer is looking for

• This question tests network troubleshooting. Works layer by layer, uses tools like ping, traceroute, packet captures and interface counters, and isolates problems methodically.
• Strong answers: Checks link utilisation over time, packet loss, jitter and latency, what traffic peaks in afternoons, wireless congestion, and quality of service settings.
• Likely follow-up: What would you do if the link was simply full?

Another way it may be asked: Calls from one office get laggy around the same time daily. What do you look into?

A structure to follow: Answer, explain, example, limits

1. Step 1

   Answer

   Give your direct answer in the first sentence so the interviewer knows where you are going.

2. Step 2

   Explain

   Say how it works or why you would do it that way, in plain words before jargon.

3. Step 3

   Example

   Anchor it in something you have actually done or seen, with the detail that shows hands-on experience.

4. Step 4

   Limits

   Say when your approach would not be the right one. It shows judgement.

This is guidance on shape, not a script. Use your own real experience and facts; never invent details to fill a gap. See the STAR guide and answer frameworks.

Common slips

• Reciting a definition without showing you have applied it.
• Using terms you cannot explain if asked a level deeper.
• Claiming experience beyond what you can discuss in detail.

How to practise it

Say the answer in 90 seconds, then answer the follow-up as if it were a new question.

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• What is a VLAN, and why would an office separate its traffic into different VLANs?
• When would you choose OSPF versus BGP, and what problems have you seen with either in practice?
• How would you set up firewall rules and segmentation for a network with guest wireless, office staff and payment terminals?

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