The questions are all concept based.
You can read all the lectures content,but what they will ask on did you actually understood the concept or not.
Take for example the concept of 2s complement.Read 2s complement.Solve questions and then solve this –
This question was asked in gate cse 2013 based on 2s complement –
The smallest integer that can be represented by an 8-bit number in 2’s complement form is _____.
If you are able to solve this question then you have fully understood the 2s c omplement.
So strong understanding of concepts should be clear.
Take another example on question on B trees
Consider a B±tree in which the maximum number of keys in a node is 5. What is the minimum number of keys in any non-root node? (GATE CS 2010)
Now try to understand B+ trees and then solve this question,if you have fully understand the concept of B
- trees then only you can solve this.
So they target your concepts,your understanding.
I hope I gave you a idea.