We assume in this section that you :

• •  Have some experience working with a relational DB ( like MySQL ).
• •  Have a basic idea about NoSQL DBs.
• •  Understand the basics of the following : 
  
  • -  Concurrency : Do you understand threads, deadlock, and starvation? What happens when multiple processes / threads are trying to modify the same data? A basic understanding of read and write locks.
  • -  Networking : Do you roughly understand basic networking protocols like TCP and UDP? Do you understand the role of switches and routers?
  • -  File systems : You should understand the systems you’re building upon. Do you know roughly how an OS, file system, and database work? Do you know about the various levels of caching in a modern OS?