Scalability - Horizontant and Vertical? Load Balancer? What is HTTP Socket? What is reverse proxy ? Components of HTTP call? What happens when you open a browser and type in the website? How to pass the state on one application to another ? How to handle the apps that doesn't have state ? Which datastore to use and why? How do you decide which database to use - relational or non relational ? Difference between encryption and hashing ? What is symmetric and asymmetric cryptography? What is fan and nest storage ? What is indexing ? Give the example of bad index. Why is it a bad index ? How does indexing work ? A connection to database is made using an app, but it's not returning a response. How do you debug this ? Hadoop Architecture. Which Big Data technologies have you worked on? Containers.