Internet 2 : Application Layer

2nd video about the Internet! I explain what is the Application Layer, the first layer in the layered architecture of the Internet.
Link to the next video on the Transport Layer: • Internet 3 : Transport...
Prerequisites:
Internet 1 : Protocols and architecture ( • Internet 1 : Protocole... )
Content:
Types of applications: client-server and peer-to-peer
Web
Electronic mail
BitTorrent
DNS
proxies and caches
Command-line terminal tutorial:
On a computer, we can interact with the operating systems and applications via what we call a terminal. We type commands we want to execute.
Depending on the operating system, we access this terminal in different ways and the syntax can be different. If you want to try as well:
Linux: Type "terminal" in the applications search bar
Windows: Type "cmd" in the search tool
Mac OS: Go to applications folder, then utility folder and open the application "terminal"
I use Linux commands in this video ("telnet" and "nslookup") which are also valid on Windows and Mac OS. Except that on Windows, "telnet" might need to be manually activated (search "windows 10 activate telnet" on Google).
References:
Computer Networking: A Top-Down Approach (6th Edition), James F. Kurose, Keith W. Ross