First round was online assessment with 5 OOPS + DB questions, 1 Leetcode medium (valid palindrome linkedlist)

Second round was video call, discussing about my work and cross questions on the same. Few more questions were:

1. how would you manage downstream unstable microservice APIs (answered: circuit breaker)
2. how to make sure write operation is DB is not lost. (answered: backup system)
3. How to maintain concurrency in database write, that is multiple servers trying to write to db simultaneously.
4. Longest path sum in Binary Tree.
5. https://leetcode.com/problems/max-area-of-island/description/

Please let me know how would you have answered above 1) to 3) questions of video call discussion.