OYO interview question

1. Round.) Databases(MongoDB, RDS) -- How would you optimize the retrieving of data from MongoDB? What if data retrieval is slow, what would you do to make it happen faster? Then, there were live scenario based questions. What if a guy comes to you and tell you that Oyo app is not working? What would you do, how would you make ensure everything is working correctly? Monitoring/Alerting: As I had worked on NewRelic, so the interviewer asked me about latency/throughput. Then there was a scripting round. I was asked to write a script to calculate average response time which appear in nginx logs. In AWS, they asked me Load Balancer in deep.(ELB, HAproxy). In Linux, they asked me about LVM. Questions related to Agile methodology were also asked. What's the difference between Agile approach and normal software development cycle.