4) Distributed/Cluster Computing
N.B-> What are some good resources for learning about distributed computing? Why?. Also IIT Bombay’s Distributed Computing courses viz. Distributed Systems, Distributed Event Based Systems and Advanced Distributed Systems – Engineering a Cloud seems quite promising.
5) Operating System
6) Database Systems
P.S. -> If one wants to have an introductory knowledge of most of the breadths of Computer Science, then he/she can refer – Invitation to Computer Science