Introduction to Networks
Introduction to Networks: A computer network is a group of computers that are digitally interconnected, for
the purpose of sharing resources (Hardware/Software).
Advantages of Computer Network
• File sharing • Resource sharing
• Sharing a single internet connection • Increasing storage capacity
Types of Networks: [1 Mark / Theory]
Type Full Form Distance Media Used Devices Used
PAN Personal Area Network 30-40 ft Bluetooth, Infrared, Data Cable
(A Room ) etc.
LAN Local Area Network 0-1 Km Wifi, Twisted Wire Pair, Switch/Hub
Ethernet Cable
MAN Metropolitan Area Network 1-15Km Coaxial Cable, Microwaves Repeaters
WAN Wide Area Network ∞ Radio Waves, Optical Fiber, Gateways, Routers
Satellite Communication
Network Devices : [1 Mark / Theory]
• NIC : A network interface controller (also known as a network interface card, network adapter, LAN
adapter or physical network interface) is a computer hardware component that connects a computer
to a computer network.
• RJ-45 : RJ45 is a type of connector commonly used for Ethernet networking.
• Modem: Modulator–Demodulator : Convert Digital Signals to Analog Waves(Modulation) at Source
and Analog waves to Digital Signals at destination (Demodulation). It Connects Computer system to a
network through telephone line.
• Hub : Act as a Central Device in Star Topology. It is a passive device
• Switch: is networking hardware that connects devices on a computer network by using packet
switching to receive and forward data to the destination device. Also Known as Intelligent Hub.
• Repeater: A repeater is an electronic device in a communication channel that increases the power of
a received signal and retransmits them, allowing them to travel further.
• Router: A router is a networking device that forwards data packets between computer networks. i.e
a router connects networks. Routers are intelligent devices, and they store information about the
networks they’re connected.
• Gateway: are used to connect networks, which may be entirely different from each other.
• Bridge : A bridge is a network device that connects multiple LANs (local area networks) together to
form a larger LAN.
Network Topology: The physical way in which computers are connected to each other in a network is called
Network Topology. [1 Marks /Theory]
Bus: A bus topology is a topology for a Local Area Network (LAN) in which all the nodes are connected to a single
cable. The cable to which the nodes connect is called a "backbone". If the backbone is broken, the entire segment
fails.
Ring: A ring topology is a network configuration where device connections create a circular data path. Each
networked device is connected to two others, like points on a circle.
Star: A star topology is a topology for a Local Area Network (LAN) in which all nodes are individually connected to
a central connection point, like a hub or a switch.
Tree: A tree topology is a special type of structure where many connected elements are arranged like the branches
of a tree.
Mesh: A mesh topology is a network setup where each computer and network device is interconnected with one
another.
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BUS Topology Ring Star Tree Mesh
Topology Topology Topology Topology
Point to remember about Topologies:
1. Adding of nodes is the easiest in Bus Topology.
2. Ring Topology provides bi-directional flow of data.
3. Start Topology has central control.
4. Shortest cable length : Bus ; Maximum cable required : Mesh
5. Mesh topology provide multiple paths from source to destination.
Introduction to Internet: The Internet is a vast network that connects computers all over the world.
URL : Uniform Resource Locator : address of a given unique resource on the Web.
e.g. http://www.example.com/index.html
Domain Name: A domain name is the permanent address of a website on the Internet.
e.g. www.yahoo.com
WWW: World Wide Web : also known as a Web, is a collection of websites or web pages stored in web
servers and connected to local computers through the internet.
Web Site: a set of related web pages located under a single domain name, typically produced by a single
person or organization.
Web: is a collection of websites or web pages stored in web servers and connected to local computers
through the internet.
Email: is an Internet service that allows people who have an e-mail address (accounts) to send and receive
electronic letters. These letters may be plain text, hypertext or images. We can also send files with email
using attachments.
Chat : is a way of communication, in which a user sends text messages through Internet. The messages can
be send as one to one communication (one sender sending message to only one receiver) or as one to
many communication (one sender sending a message to a group of people)
VoIP: Voice over Internet Protocol: is a technology that allows you to make voice calls using an Internet
connection instead of a regular (or analog) phone line.
Difference between a Website and webpage
Webpage Website
Webpage is a single document on the Internet Website is a collection of multiple webpages with
information on a related topic
Each webpage has a unique URL. Each website has a unique Domain Name
Static Web Page: A static web page (sometimes called a flat page or a stationary page) is a web page that is
delivered to the user's web browser exactly as stored. i.e. static Web pages contain the same prebuilt content
each time the page is loaded
Dynamic web page: The contents of Dynamic web page are constructed with the help of a program. They may
change each time a user visit the page. Example a webpage showing score of a Live Cricket Match.
Web Server: Web server is a computer where the web content is stored. Basically web server is used to host
the web sites
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Hosting of a Website: When a hosting provider allocates space on a web server for a website to store its files,
they are hosting a website. Web hosting makes the files that comprise a website (code, images, etc.) available
for viewing online
Web Browser: A web browser (commonly referred to as a browser) is a software application for accessing
information on the World Wide Web. e.g. Internet Explorer, Google Chrome, Mozilla Firefox, and Apple Safari.
Add-ons/plug-ins : is a software component that adds a specific feature to an existing computer program.
Cookies: are combination of data and short codes, which help in viewing a webpage properly in an easy and fast
way. Cookies are downloaded into our system, when we first open a site using cookies and then they are stored
in our computer only. Next time when we visit the website, instead of downloading the cookies, locally stored
cookies are used. Though cookies are very helpful but they can be dangerous, if miss-utilized.
Protocols: Protocols are set of rules, which governs a Network communication. Or set of rules that determine
how data is transmitted between different devices in a network.
HTTP : Hyper Text Transfer Protocol : HTTP offers set of rules and standards which govern how any
information can be transmitted on the World Wide Web
HTTPs : Hypertext Transfer Protocol Secure: It is advanced and secure version of HTTP.
TCP/IP : Transmission Control Protocol / Internet Protocol : determine how a specific computer should be
connected to the internet and how data should be transmitted between them.
FTP : File Transfer Protocol : Transfer file(Upload/ Download) files to or from a remote server.
SMTP : Simple Mail Transfer Protocol : purpose is to send, receive, mail between email senders and
receivers.
POP3 : Post Office Protocol version 3 : standard protocol for receiving e-mail.
VoIP : Voice Over Internet Protocol :
HTTP HTTPs
HTTP is unsecured HTTPS is secured
HTTP sends data over port 80 HTTPS uses port 443
Hints to solve Case Study based Question: [5 Marks Generally last ques. in QP]
Question Type Hint Answer
Circuit Diagram Connects all the units in the question with a unit having
maximum no. of computers
Best Place to host Server Unit having Maximum no. of computers
Placing of Switch/Hub In each unit
Placing of Repeater Between units where distance is more than 100m
Most economical Communication Broadband
medium
Communication media for small Ethernet Cable
Distance < 100 m
Communication Media for Radio Waves,
Desert areas
Communication Media for Hilly Radio Waves/ Microwaves
Areas
Hardware/Software to prevent Firewall
unauthorized access
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