(i) Network Access Layer - concerned with building packets. 
(ii) Internet Layer - describes how packets are to be delivered.
(iii) Transport Layer - ensure the proper transmission of data. 
(iv) Application Layer - application network processes. These processes include File Transfer Protocol (FTP), Hypertext Transfer Protocol, (HTTP), and Simple Mail Transfer Protocol (SMTP).

It is a private network that uses Internet technology and the public tele communication system to securely share business's information with suppliers, vendors, partners, customers, or other businesses

(i) It Resolves IP addresses to MAC (Medium Access Control) addresses .
(ii) A MAC address is a hardware identification number that uniquely identifies each device on a network.

(i)  A mobile network or cellular network as it is made up of a large number of signal areas called cells.
(ii) These cells join to form a large coverage area. Users can cross into different cells without losing their connection.

Network protocols is that the usual procedures, rules, formal standards and policies comprised of formats which allocates communication between more than one device which connected to the network.