When you were in school and you were ready to take a test, you would get ready for the test by taking notes. And it was through these notes that you would really start to learn the material that your teacher had been try to teach all week. And sometimes if you were lucky, when it came time to take the test, the teacher would allow you to use the notes that you took in an open notes test. This is where it would really pay off to take good notes. That is what real life is like when you are dealing with complicated issues. You are allowed to take notes and use them in case of an emergency. People are more concerned that you get it right more than they are if you memorized the issue or not.
When you are dealing with computer security you should be taking a lot of real notes to help you in your job. Computers are very complicated machines and there are a lot of layers to them. There is no way that anyone is going to be able to specialize in all of them. You have your specialties and then you have your general knowledge about the rest of the system. It is because of this that it is a good idea to take notes as often as you can.
When something happens to the computer or your network and it is affecting more than one layer of the system, you want to be prepared. You want to be able to dig down into the system and be able to diagnose what is wrong. If the problem is complicated enough you will not be able to do that just by pure memory alone. You are going to need some help.
It does not matter if your notes are underlined in a book or real life note taking. Just as long as you have a reference point to start with you should be fine. As long as you have something that you are first of all comfortable with it and second of all able to access within a few minutes’ notice you should be ok.
If you want to be god job then you are going to have to take a lot of notes. Computer security has a lot of moving parts and there is no way that you are going to know all of them.