Wow, it was tough. Really, really.. It's a great lecture. I used to study networks by myself and struggled with them, but I felt like things weren't organized, but after listening to this lecture, I was able to organize my thoughts on networks well.! I have a question. I wonder if you are producing a separate lecture on network security.! I definitely want to find this and listen to the instructor's lecture. I learned a lot. Thank you.!!