An app server in a private subnet cannot reach an external payment service. How do you troubleshoot that connection?

What the interviewer is looking for

• This question tests cloud networking. Explains virtual networks, subnets, routing, gateways, security groups and DNS, and troubleshoots connectivity step by step.
• Strong answers: Route tables and NAT, security groups and network rules, DNS resolution, provider allow lists, flow logs, and testing from the instance.
• Likely follow-up: What logs or tools in the cloud would help you prove where traffic stops?

Another way it may be asked: Your server needs to call a payment company's website, but the calls time out. What do you check?

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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