Provides reliable connection oriented ransmission between two hosts. It guarantees delivery of packets between the hosts. 

(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).

(i)  Internet Protocol (IP) is the principle of the communications protocol in the Internet protocols for layering on datagram across boundaries of other networks.
(ii)The main function is to allows Internet working and boost up the Internet.

(i) It provides mobility.
(ii) It provides connection to Internet.
(iii) Flexibility of LAN.
(iv) Ensures connectivity.
(v) Low cost, high benefits.

The common application of mobile networks is mobile phones, tablets, etc.. In the past, wireless communications largely used circuit switching to carry only voice over a network, but now currently both data and voice are being transmitted over both circuit via switched networks and packet switched networks.

(i) Wi-Fi stands for Wireless Fidelity.
(ii) It is a wireless network technology that permits computers and alternative devices to be connected to every alternative into a local area network and to the net without wires and cables .
(iii) Wi-Fi is additionally stated as wireless local area network that stands for wireless local area network, and 802.11, that is that the technical code for the protocol.

(i) They had a very low traffic density of one call per radio channel,
(ii) A very poor voice quality.
(iii) They used unsure and unencrypted transmission, which leads to the spoofing of its identities

(i) UDP- User Datagram Protocol
(ii) DNS - Domain Name System
(iii) OSI – Open System Interconnection
(iv) RFID- Radio Frequency Identification

(i) HTTP: A protocol used between a web client and a web server protects non-secure data transmissions. The core protocol of the World Wide Web.
(ii) HTTPS: A protocol used between a web client and a web server permits secure data transmissions.
(iii) FTP: Used between computers for sending and receiving data. Enables a client to send and receive complete files from a server.

Comparision between Internet, intranet and Extranet

(i) SG is the stage succeeds the 4G (LTE/WiMAx), 3G(umts) and 2G(GSM)syetems.
(ii) SG targets to performance the high data rate, reduced latency, energy saving, cost reduction, higher system, capacity, and massive device connectivity.
(iii) The two phasesof SG,First one will be Release-1S complete by March 2019, Second one Release- 16is expected to complete at March2020, for submission to the ITU (International Telecommunication Union) as a candidate IMT- 2020 technology.
(iv)  The ITU IMT - 2020 provides speeds up to 20 gigabits per second it has been demonstrated with millimeter waves of lS giga hertz and higher frequency. 3 GPPstandards includes any network using the New Radio software. SGNew Radio can accessat lower frequencies from 600 MHzto 6 GHz.
(v) Speed in the lower frequencies are only modest higher than 4G systems, estimated at lS% to SO%faster

(i)  The second generation of mobile systems was placed on digital transmission with GSM.
(ii) GSM stands for (Global System for Mobile communication) was most popular standard which is used in second generation, using 900MHl and 1800MHz for the frequency bands.
(iii) GSM mobile systems grown digital transmission using SIM. SIM stands for (Subscriber Identity Module) technology to authenticate a user for identification and bllling purposes and to encrypt the data to prevent listen without permission (eaves dropping).
(iv)  The transmission used as TDMA. TMDA stands for (Time Division Multiple Access) and CDMA One stands for (Code Division MultipleAccess ) method to increase the amount of information transported on the network.
(v) Mobility is supported at layer 2, which stops seamless roaming across assorted access networks and routing domains. This means each operator must cover the entire area or have agreements in place to permit roaming.

Development of Mobile Networks :
The generations of mobile networks are as follows.
(i) First Generation(1G) 1981- NMT launch
(ii) Second Generation(2G) 1991-GSM Launch
(iii) Second to Third Generation Bridge (2.5)2000 — GPRS launch
(iv) Third Generation( 3G) 2003- UK 3G launch
(v) Fourth Generation (4 G) 2007
(vi) Fifth Generation (5G) 2019+
Merits of Mobile Networks :
(i) It provides both voice/data services.
(ii) It connects both fixed and wireless telephone users.
(iii) It is used in areas where cables cannot be laid out due to its wireless nature.
(iv) It is easy to maintain.
(v) It is easy to upgrade the equipments.
(vi) The ‘mobile and fixed subscribers are connected immediately with cellular network as soon as mobile phones are switched on.
(vii) All the handshake signals between mobile and base station are automatically exchanged.
Demerits of Mobile Networks :
(i) Cost
(ii) Vulnerable to Security risks
(iii) Additional training is needed to use new technology.
(iv) Cyber Crime.

INTERNET:
(i) The Internet is a worldwide system of computer networks- A network of networks where the users at any one computer can get information from any other computer.
(ii) The Internet is a network of global connections - comprising private, public, business, academic and government networks connected by guided, wireless and fiber-optic technologies.
(iii) The unique aim was to generate a network that would permit users of a research computer from one university to "talk to" research computers on other universities.
(iv) The Internet denotes to the global communication system, including infrastructure and hardware, whereas the web is one of the services interconnected over the Internet.
INTRANET:
(i) Intranet is a private network within an enterprise to share company data and computing resources between the employees.
(ii) It may consist of many interlinked local area networks.
(iii) It includes connections through one or more gateway (connects two networks using different protocols together known as protocol convertor) computers to outside Internet.
EXTRANET: Extranet is a private network that uses Internet technology and the public telecommunication system to securely share business information with suppliers, vendors, partners, customers, or other business.