Randomly tell me what should I study to cover application layer?

Oh man! Ad-blocking software has been detected! :'(

This website is run by the community, for the community... and it needs advertisements in order to keep running. Blocking our ads means your killing our stats!
Please disable your ad-block, or become a premium member to hide all advertisements and this notice.

I got no idea about what to study. I know even you've got no idea but use your experience and tell me learning what would be useful (Not for exam but in real life as well as a linux admin).
The exam is going to be very easy, so I don't care about exam.

5.5 Application layer: Web (HTTP & HTTPS), File Transfer (FTP, PuTTY, Win SCP), Electronic Mail,
DNS, P2P Applications, Socket Programming, Application server concept, and Concept of traffic
analyzer (MRTG, PRTG, SNMP, Packet tracer, Wireshark).

This comes for 2 marks in our Engineering License Exam

The questions from here are going to be very easy like thisCan't share link)

Problem is I've already bought good books on this subject and I am very much interested in learning computer networking.


So, I want to learn them in depth. Can you give me a roadmap of what should I cover in these topics?

For example, while learning about HTTP, what topics should I cover? When learning about DNS, what topics should I cover? These subjects have whole books of their own. But just tell me stuffs that I can learn within 25 pages of a textbook.