What’s the most challenging/exciting project you have done in the past two years?

Technical screeners are asking this question to see what you consider a challenge and how you approach challenging projects, what you like, what you don't like.

Use it as an opportunity to present yourself in the best light possible. Candidates are often not able to describe past challenges with good level of detail, which is undermining their credibility ("What was he doing? He wasn't able to explain any challenge, does it mean that he was working just on the trivial tasks or he lacks communication skills?")