Its confusing that the text first talks about seven layers and than only describes four. True: the ubiquitous tcp/ip - stack only knows the four mentioned layers but it sbould be explained why only four are described. Theking2 (talk) 09:31, 23 February 2018 (UTC)
Layer 1: Physical layer[change source]
Coaxial cables to provide broadband Internet. Broadband Internet for home users won't need coaxial cables. If 10BASE2 was meant than this part is more confusing that explaining.