BQ: How do you react when something unforeseen occurs?

Tell me about a time when you had an unexpected event that required you to change your priorities.
Similar interview questions:
How do you react when something unforeseen occurs?
What happens when you need to quickly change what you are doing in your work?
Give me an example of when you went into firefighting mode.
Who is the best person on your team to respond in a time of emergency?

Why the interviewer is asking this question:
This question is not only about how you responded to the unexpected, but also whether there was anything you could have done to better prepare for or even avoid the unexpected event. The interviewer will also be looking for how you might have made changes to respond to such events in the future.

The best approach to answering this question:
Most jobs have an element of daily firefighting involved in responding to needs. Some jobs more than others. The key to answering this question is to select an event that could not have been planned for in advance which you were able to successfully solve. Another option would be a situation where you helped out another team in emergency mode. Ideally, it is also an event for which you not only solved but also worked out a way to handle it if and when it occurs again in the future.

An example of how to best answer this question for experienced candidates:
“We had a recent event which caused system downtime for our entire company and our user base. We had switched to a cloud services provider primarily to minimize our downtime. They had multiple layers of redundancy which we could not provide internally. So it was both ironic and unexpected when the cloud services provider was hit with a denial of service attack that shut down the entire network of sites. We were affected, along with a large number of other companies. We were completely offline for over two hours. I worked with our IT team and the cloud services provider to minimize the impact to our users by temporarily shifting traffic to our local servers through a manual IP shift that we organized on the fly. We also used our learnings from the event to set up an automated IP shift if the problem occurs again in the future…”

An example of how to best answer this question for entry-level candidates:
“On my recent internship, we had an all-hands-on-deck request when one of the customers put in an unexpectedly large order which needed to be fulfilled within 24 hours. Our team mobilized to assist in fulfilling the order and literally worked around the clock to make it happen. I learned a great deal about exceeding customer expectations during that time and our team also worked out a process document covering our lessons learned so that this type of situation could be handled more efficiently in the future…”

An example of how you should not answer this question:
“Well, one of the systems I worked on last year crashed and they called me to help them fix it. I had to make the decision on whether to continue doing my own work or help them. I knew I wouldn’t be able to get my regular work done, so I told them to read the documentation and figure it out. Although I already knew that the documentation wasn’t very good and probably wouldn’t help them. Finally, they got frustrated and left me alone. I didn’t really like working with that user group anyway, so I didn’t feel bad about burning bridges with them…”