OSI network model

• https://www.youtube.com/watch?v=7IS7gigunyI

• http://www.javaperspective.com/the-osi-model.html

• https://stackoverflow.com/questions/42456116/understanding-tcp-ip-layering-through-internet-flow

• http://www.javaperspective.com/ip-addresses-dns-and-port-numbers.html

• https://medium.com/@james_aka_yale/the-4-layer-internet-model-network-engineers-need-to-know-e78432614a4f