List the 7 layers of the OSI model. A very common and important question. From bottom to top: Physical, Data Link, Network, Transport, Session, Presentation, Application.

 

What is a WAN? A WAN (Wide Area Network) is a global area network that is not limited by geographic location - apartment, floor or building. A great example of a WAN is the Internet, through which you are reading this article.

 

What is the maximum length of a UTP cable? One arm of the cable works up to 100 meters. Then you need a repeater or a switch.

 

What is a router? A router (router, because it is the same thing) is a layer 3 device in the OSI model that routes IP packets between subnets. A router remembers routing tables, distance to other subnets, bottlenecks, and other parameters.