CBSE Class 12 Computer Science Communication And Network Concepts Notes

Communication and Network Concepts Class 12 Notes

Network

• The collection of interconnected computers is called a computer network.

• Two computers are said to be interconnected if they are capable of sharing and exchanging information.

Need

• Resource Sharing

• Reliability

• Cost Factor

• Communication Medium

Resource Sharing means to make all programs, data and peripherals available to anyone on the network irrespective of the physical location of the resources and the user. Reliability means to keep the copy of a file on two or more different machines, so if one of them is unavailable (due to some hardware crash or any other) them its other copy can be used. Cost factor means it greatly reduces the cost since the resources can be shared Communication Medium means one can send messages and whatever the changes at one end are done can be immediately noticed at another.

Evolution of Networking

1. ARPANET:In 1969, The US govt. formed an agency named ARPANET (Advanced Research Projects Agency NETwork) to connect computers at various universities and defense agencies. The main objective of ARPANET was to develop a network that could continue to function efficiently even in the event of a nuclear attack.

2. Internet (INTERconnection NETwork): The Internet is a worldwide network of computer networks. It is not owned by anybody.

3. Interspace:InterSpace is a client/server software program that allows multiple users to communicate online with real – time audio, video and text chat in dynamic 3D environments.

SWITCHING TECHNIQUES

Switching techniques are used for transmitting data across networks.

Different types are :

1. Circuit Switching: In the Circuit Switching technique, first, the complete end-to-end transmission path between the source and the destination computers is established and then the message is transmitted through the path. The main advantage of this technique is guaranteed delivery of the message. Mostly used for voice communication.

2. Message Switching: In the Message switching technique, no physical path is established between sender and receiver in advance. This technique follows the store and forward mechanism.

3. Packet Switching: In this switching technique fixed size of packet can be transmitted across the network

DATA COMMUNICATION TERMINOLOGIES

Data channel :- The information / data carry from one end to another in the network by channel.
Baud & bits per second (bps) :- It’s used to measurement for the information carry of a communication channel.
Measurement Units :- bit
1 Byte= 8 bits
1 KBPS ( Kilo Byte Per Second)= 1024 Bytes
1 Kbps (kilobits Per Second) = 1024 bits
1 Mbps ( Mega bits Per Second )=1024 Kbps
Bandwidth :- It is amount of information transmitted or receives per unit time.

Transmission media:

1. Twisted pair cable: - It consists of two identical 1 mm thick copper wires insulated and twisted together. The twisted pair cables are twisted in order to reduce crosstalk and electromagnetic induction.

Advantages:
(i) It is easy to install and maintain.
(ii) It is very inexpensive
Disadvantages:
(i) It is incapable to carry a signal over long distances without the use of repeaters.
(ii) Due to low bandwidth, these are unsuitable for broadband applications.

2. Co-axial Cables: It consists of a solid wire core surrounded by one or more foil or braided wire shields, each separated from the other by some kind of plastic insulator. It is mostly used in the cable wires.

Advantages:
(i) Data transmission rate is better than twisted pair cables.
(ii) It provides a cheap means of transporting multi-channel television signals around metropolitan areas.
Disadvantages:
(i) Expensive than twisted pair cables.
(ii) Difficult to manage and reconfigure.

3. Optical fiber: - An optical fiber consists of thin glass fibers that can carry information in the form of visible light.

Advantages:
(i) Transmit data over long distance with high security.
(ii) Data transmission speed is high
(iii) Provide better noise immunity
(iv) Bandwidth is up to 10 Gbps.
Disadvantages:
(i) Expensive as compared to other guided media.
(ii) Need special care while installation?

4. Infrared: - The infrared light transmits data through the air and can propagate throughout a room, but will not penetrate walls. It is a secure medium of signal transmission.
The infrared transmission has become common in TV remotes, automotive garage doors, wireless speakers etc.

5. Radio Wave: - Radio Wave an electromagnetic wave with a wavelength between 0.5 cm and 30,000m. The transmission making use of radio frequencies is termed as radio-wave transmission

Advantages:
(i) Radio wave transmission offers mobility.
(ii) It is cheaper than laying cables and fibers.
(iii) It offers ease of communication over difficult terrain.
Disadvantages:
(i) Radio wave communication is insecure communication.
(ii) Radio wave propagation is susceptible to weather effects like rains, thunder storms etc.

6. Microwave Wave: - The Microwave transmission is a line of sight transmission. Microwave signals travel at a higher frequency than radio waves and are popularly used for transmitting data over long distances.
Advantages:
(i) It is cheaper than laying cable or fiber.
(ii) It has the ability to communicate over oceans.
Disadvantages:
(i) Microwave communication is an insecure communication.
(ii) Signals from antenna may split up and transmitted in different way to different antenna which leads to reduce to signal strength.
(iii) Microwave propagation is susceptible to weather effects like rains, thunder storms etc.
(iv) Bandwidth allocation is extremely limited in case of microwaves.

7. Satellite link: - The satellite transmission is also a kind of line of sight transmission that is used to transmit signals throughout the world.
Advantages:
(i) Area covered is quite large.
(ii) No line of sight restrictions such as natural mountains, tall building, towers etc.
(iii) Earth station which receives the signals can be fixed position or relatively mobile.
Disadvantages:-
(i) Very expensive as compared to other transmission mediums.
(ii) Installation is extremely complex.
(iii) Signals sent to the stations can be tampered by external interference.
Network devices:
Modem: A MODEM (MOdulator DEModulator) is an electronic device that enables a computer to transmit data over telephone lines. There are two types of modems, namely, internal modem and external modem.
RJ45 connector: - The RJ-45(Registered Jack) connectors are the plug-in devices used in the networking and telecommunications applications. They are used primarily for connecting LANs, particularly thernet.
Ethernet Card: - It is a hardware device that helps in connection of nodes within a network.
Hub: A hub is a hardware device used to connect several computers together. Hubs can be either active or passive. Hubs usually can support 8, 12 or 24 RJ45 ports.
Switch: A switch (switching hub) is a network device which is used to interconnect computers or devices on a network. It filters and forwards data packets across a network. The main difference between hub and switch is that hub replicates what it receives on one port onto all the other ports while switch keeps a record of the MAC addresses of the devices attached to it.
Gateway: A gateway is a device that connects dissimilar networks.
Repeater: A repeater is a network device that amplifies and restores signals for long distance transmission.

Network topologies and types

Topology :
· Topology refers to the way in which the workstations attached to the network are interconnected.
The BUS Topology: - The bus topology uses a common single cable to connect all the workstations. Each computer performs its task of sending messages without the help of the central server. However, only one workstation can transmit a message at a particular time in the bus topology.
Advantages:
(i) Easy to connect and install.
(ii) Involves a low cost of installation time.
(iii) Can be easily extended.
Disadvantages:-
(i) The entire network shuts down if there is a failure in the central cable.
(ii) Only a single message can travel at a particular time.
(iii) Difficult to troubleshoot an error.
The STAR Topology: - A STAR topology is based on a central node which acts as a hub. A STAR topology is common in homes networks where all the computers connect to the single central computer using it as a hub.
Advantages:
(i) Easy to troubleshoot
(ii) A single node failure does not affect the entire network.
(iii) Fault detection and removal of faulty parts is easier.
(iv) In case a workstation fails, the network is not affected.
Disadvantages:-
(i) Difficult to expand.
(ii) Longer cable is required.
(iii) The cost of the hub and the longer cables makes it expensive over others.
(iv) In case hub fails, the entire network fails.
The TREE Topology: - The tree topology combines the characteristics of the linear bus and the star topologies. It consists of groups of star – configured workstations connected to a bus backbone cable.
Advantages:
(i) Eliminates network congestion.
(ii) The network can be easily extended.
(iii) Faulty nodes can easily be isolated from the rest of the network.
Disadvantages:
(i) Uses large cable length.
(ii) Requires a large amount of hardware components and hence is expensive.
(iii) Installation and reconfiguration is very difficult.

Types of Networks:

LAN (Local Area Network): A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as writing lab, school or building. It is generally privately owned networks over a distance not more than 5 Km.
MAN (Metropolitan Area Network): MAN is the networks cover a group of nearby corporate offices or a city and might be either private or public.
WAN (Wide Area Network): These are the networks spread over large distances, say across countries or even continents through cabling or satellite uplinks are called WAN.
PAN (Personal Area Network): A Personal Area Network is computer network organized around an
individual person. It generally covers a range of less than 10 meters. Personal Area Networks can be
constructed with cables or wirelessly.

Network protocol

· A protocol means the rules that are applicable for a network.
· It defines the standardized format for data packets, techniques for detecting and correcting errors and so on.
· A protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
· E.g. using library books.

Types of protocols are:

1. HTTP
2. FTP
3. TCP/IP
4. SLIP/PPP
· Hypertext Transfer Protocol (HTTP) is a communications protocol for the transfer of information on the intranet and the World Wide Web. HTTP is a request/response standard between a client and a server. A client is the end-user; the server is the web site.
· FTP (File Transfer Protocol) is the simplest and most secure way to exchange files over the Internet. The objectives of FTP are:
· To promote sharing of files (computer programs and/or data).
· To encourage indirect or implicit use of remote computers.
· To shield a user from variations in file storage systems among different hosts.
· To transfer data reliably, and efficiently.
· TCP/IP (Transmission Control Protocol / Internet Protocol)
TCP - is responsible for verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP adds support to detect errors or lost data and to trigger retransmission until the data is correctly and completely received.
IP - is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address (the IP number). The Internet authorities assign ranges of numbers to different organizations. The organizations assign groups of their numbers to departments. IP operates on gateway machines that move data from department to organization to region and then around the world.

Telnet-
It is an older internet utility that lets us log on to remote computer system. It also facilitates for terminal emulation purpose. Terminal emulation means using a pc like a mainframe computer through networking.

Wireless/Mobile Computing

Wireless communication is simply data communication without the use of landlines. Mobile computing means that the computing device is not continuously connected to the base or central network.
1. GSM(Global System for Mobile communication): it is leading digital cellular system. In covered areas, cell phone users can buy one phone that will work any where the standard is supported. It uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency.
2. CDMA(Code Division Multiple Access): it is a digital cellular technology that uses spreadspectrum techniques. CDMA does not assign a specific frequency to each user. Instead ,every 
3. WLL(Wireless in Local Loop) : WLL is a system that connects subscribers to the public switched telephone network using radio signals as a substitute for other connecting media.
4. Email(Electronic Mail): Email is sending and receiving messages by computer.
5. Chat: Online textual talk in real time , is called Chatting.
6. Video Conferencing: a two way videophone conversation among multiple participants is called video conferencing.
7. SMS(Short Message Service): SMS is the transmission of short text messages to and from a mobile pone, fax machine and or IP address.
8. 3G and EDGE: 3G is a specification for the third generation of mobile communication of mobile communication technology. 3G promises increased bandwidth, up to 384 Kbps when a device is stationary.
EDGE(Enhanced Data rates for Global Evolution ) is a radio based high speed mobile data standard.

Network Security Concepts:

Viruses: Viruses are programs which replicate and attach to other programs in order to corrupt the executable codes. Virus enters the computer system through an external source and become destructive.
Worms: Worms are also self- replicating programs that do not create multiple copies of itself on one computer but propagate through the computer network. Worms log on to computer systems using the username and passwords and exploit the system.
Trojan horse: - Though it is a useful program, however, a cracker can use it to intrude the computer system in order to exploit the resources. Such a program can also enter into the computer through an email or free programs downloaded through the Internet.
Spams: Unwanted e-mail (usually of a commercial nature sent out in bulk)
Cookies: Cookies are the text messages sent by a web server to the web browser primarily for identifying the user.
Firewall: A firewall is used to control the traffic between computer networks. It intercepts the packets between the computer networks and allows only authorized packets to pass.
Cyber Law: Cyber law refers to all the legal and regulatory aspects of Internet and the World Wide Web.
Cyber Crimes: Cyber crime involves the usage of the computer system and the computer network for criminal activity.
Hacking: Hacking is an unauthorized access to computer in order to exploit the resources.

Web Services:

WWW: The World Wide Web or W3 or simply the Web is a collection of linked documents or pages, stored on millions of computers and distributed across the Internet.
HTML (Hyper Text Markup Language):- HTML is a computer language that describes the structure and behavior of a web page. This language is used to create web pages.
XML (eXtensible Markup Language):- Extensible Markup Language (XML) is a meta language that helps to describe the markup language.
HTTP (Hyper Text Transfer Protocol):- A protocol to transfer hypertext requests and information between servers and browsers.
Domain Names: A domain name is a unique name that identifies a particular website and represents the name of the server where the web pages reside.
URL:- The Uniform Resource Locator is a means to locate resources such as web pages on the Internet.
URL is also a method to address the web pages on the Internet. There are two types of URL, namely, absolute URL and relative URL.
Website: A collection of related web pages stored on a web server is known as a website.
Web browser: A software application that enables to browse, search and collect information from the Web is known as Web browser.
Web Servers: The web pages on the Internet are stored on the computers that are connected to the Internet. These computers are known as web servers.
Web Hosting: - Web Hosting or website hosting is the service to host, store and maintain the websites on the World Wide Web.
Web Scripting: - The process of creating and embedding scripts in a web page is known as Web
Scripting. Types of Scripts:-
(i) Client Side Scripts: - Client side scripts supports interaction within a webpage. E.g. VB Script, Java Script, PHP (PHP􂀟S Hypertext Preprocessor).
(ii) Server Side Scripts: - Server side scripting supports execution at server – end. E.g. ASP, JSP, PHP

OPEN SOURCE TERMINOLOGIES

• Free Software: The S/W’s is freely accessible and can be freely used changed improved copied and distributed by all and payments are needed to make for free S/W.
• Open Source Software: S/w whose source code is available to the customer and it can be modified and redistributed without any limitation .OSS may come free of cost but nominal charges has to pay nominal charges (Support of S/W and development of S/W).
• FLOSS (Free Libre and Open Source Software) : S/w which is free as well as open source S/W. ( Free S/W + Open Source S/W).
• GNU (GNU’s Not Unix) : GNU project emphasize on the freedom and its objective is to create a system compatible to UNIX but not identical with it.
• FSF (Free Software Foundation) : FSF is a non –profit organization created for the purpose of the free s/w movement. Organization funded many s/w developers to write free software.
• OSI (Open Source Initiative) : Open source software organization dedicated to cause of promoting open source software it specified the criteria of OSS and its source code is not freely
available.
• W3C(World Wide Web Consortium) : W3C is responsible for producing the software standards for World Wide Web.
• Proprietary Software: Proprietary Software is the s/w that is neither open nor freely available, normally the source code of the Proprietary Software is not available but further distribution and modification is possible by special permission by the supplier.
• Freeware: Freeware are the software freely available , which permit redistribution but not modification (and their source code is not available). Freeware is distributed in Binary Form
(ready to run) without any licensing fees.
• Shareware: Software for which license fee is payable after some time limit, its source code is not available and modification to the software are not allowed.
• Localization: localization refers to the adaptation of language, content and design to reflect local cultural sensitivities .e.g. Software Localization: where messages that a program presents to the user need to be translated into various languages.
• Internationalization: Opposite of localization.

OPEN SOURCE / FREE SOFTWARE

• Linux : Linux is a famous computer operating system . popular Linux server set of program – LAMP(Linux, Apache, MySQL, PHP)
• Mozilla : Mozilla is a free internet software that includes
· a web browser
· an email client
· an HTML editor
· IRC client
• Apache server: Apache web server is an open source web server available for many platforms such as BSD, Linux, and Microsoft Windows etc.
· Apache Web server is maintained by open community of developers of Apache software foundation.
• MYSQL : MYSQL is one of the most popular open source database system. Features of MYSQl :
· Multithreading
· Multi –User
· SQl Relational Database Server
· Works in many different platform
• PostgreSQL : Postgres SQL is a free software object relational database server . PostgresSQL can be downloaded from www.postgressql.org.
• Pango : Pango project is to provide an open source framework for the layout and rendering of internationalized text into GTK + GNOME environment.Pango using Unicode for all of its
encoding ,and will eventually support output in all the worlds major languages.
• OpenOffice : OpenOffice is an office applications suite. It is intended to compatible and directly complete with Microsoft office.
OOo Version 1.1 includes:
· Writer (word processor)
· Calc(spreadsheet)
· Draw(graphics program)etc
• Tomcat : Tomcat functions as a servlet container. Tomcat implements the servlet and the JavaServer Pages .Tomcat comes with the jasper compiler that complies JSPs into servlets.
• PHP(Hypertext Preprocessor) : PHP is a widely used open source programming language for server side application and developing web content.
• Python: Python is an interactive programming language originally as scripting language for Amoeba OS capable of making system calls.

Please refer to attached file for CBSE Class 12 Computer Science Communication And Network Concepts

Question 1. Knowledge Supplement Organisation has set up its new center at Mangalore for its office and web based activities. It has 4 blocks of buildings as shown in the diagram below: Block A, Block B, Block C, Block D. Center to center distances between various blocks: Block A to Block B = 50 m, Block B to Block C = 150 m, Block C to Block D = 25 m, Block A to Block D = 170 m, Block B to Block D = 125 m, Block A to Block C = 90 m. Number of Computers: Block A = 25, Block B = 50, Block C = 125, Block D = 10.
- Suggest a cable layout of connections between the blocks.
- Suggest the most suitable place (i.e. block) to house the server of organisation with a suitable reason.
- Suggest the placement of the following devices with justification: Repeater, Hub/Switch.
- The organization is planning to link its front office situated in the city in a hilly region where cable connection is not feasible, suggest an economic way to connect it with reasonably high speed?
Answer:
(i) Cable Layout:
Layout Option 1: Block A connected to Block B, Block B connected to Block C, and Block C connected to Block D.
Layout Option 2: Block A connected to Block C, Block C connected to Block B, and Block C connected to Block D.
(ii) Server Placement:
Block C is the most suitable place to house the server because it contains the maximum number of computers (125), which minimizes the total cabling cost and maximizes network efficiency for the majority of nodes.
(iii) Device Placement:
- Repeater: For Layout 1, repeaters are needed between Block A and Block C, and between Block B and C due to large distances to avoid signal loss. For Layout 2, a repeater is needed between Block A and Block C.
- Hub/Switch: A hub/switch must be placed in every block to interconnect the group of computers within that block.
(iv) Connection for Hilly Region:
Radio wave transmission is the most economical and effective way to connect the front office in a hilly region because it offers mobility, penetrates buildings easily, and does not require a physical line of sight or cable laying.
In simple words: The server goes where most computers are, and radio waves are best for hilly areas without cables.

Exam Tip: Always place the server in the building with the maximum number of computers to satisfy the 80-20 rule and reduce cable costs.

Question 2. Ravya Industries has set up its new center at Kaka Nagar for its office and web based activities. The company compound has 4 buildings: Harsh Building, Raj Building, Fazz Building, and Jazz Building. Center to center distances: Harsh to Raj = 50 m, Raj to Fazz = 60 m, Fazz to Jazz = 25 m, Jazz to Harsh = 170 m, Harsh to Fazz = 125 m, Raj to Jazz = 90 m. Number of Computers: Harsh = 15, Raj = 150, Fazz = 15, Jazz = 25.
e1) Suggest a cable layout of connections between the buildings.
e2) Suggest the most suitable place (i.e. block) to house the server of this organisation with a suitable reason.
e3) Suggest the placement of the following devices with justification: (i) Internet Connecting Device/Modem, (ii) Switch.
e4) The organisation is planning to link its sale counter situated in various parts of the same city, which type of network out of LAN, MAN or WAN will be formed? Justify your answer.
Answer:
(e1) Cable Layout:
Layout Option 1: Harsh Building connected to Raj Building, Raj Building connected to Fazz Building, and Fazz Building connected to Jazz Building.
(e2) Server Placement:
Raj Building, because it contains the maximum number of computers (150), minimizing cabling costs and maximizing efficiency.
(e3) Device Placement:
(i) Modem should be placed in Raj Building where the server is installed.
(ii) A hub/switch must be placed in all buildings to interconnect computers locally.
(e4) Network Type:
MAN (Metropolitan Area Network), because MAN links computer facilities and sales counters distributed across various parts within the same city.
In simple words: Put the server in Raj Building, use switches in every building, and connect city-wide counters using a MAN.

Exam Tip: Distinguish clearly between LAN (within a building/campus), MAN (within a city), and WAN (across countries/continents).

Question 3. "China Middleton Fashion" is planning to expand their network in India, starting with two cities. Main office units in Chennai are Production Unit, Finance Unit, and Media Unit. Corporate unit is in New Delhi. Approximate distances: Production to Finance = 70 Mtr, Production to Media = 15 KM, Production to Corporate = 2112 KM, Finance to Media = 15 KM. Number of computers: Production = 150, Finance = 35, Media = 10, Corporate = 30.
i) Suggest the kind of network required (out of LAN, MAN, WAN) for connecting each of the following office units: Production Unit and Media Unit, Production Unit and Finance Unit.
ii) Which one of the following devices will you suggest for connecting all the computers within each of their office units? Switch/Hub, Modem, Telephone.
iii) Which of the following communication media, will you suggest to be procured by the company for connecting their local offices in Chennai for very effective (High Speed) communication? Ethernet cable, Optical fiber, Telephone cable.
iv) Suggest a cable/wiring layout for connecting the company's local office units located in Chennai. Also, suggest an effective method/technology for connecting the company's office unit located in Delhi.
Answer:
(i) Network Types:
- Production Unit and Media Unit (15 KM): MAN
- Production Unit and Finance Unit (70 Mtr): LAN
(ii) Connecting Device:
Switch/Hub
(iii) Communication Media:
Optical fiber (due to high speed and long distance capability across the city)
(iv) Layout and Delhi Connection:
- Local Chennai offices: Optical Fiber with Star Topology.
- Delhi Corporate Unit connection: Satellite Link or Leased Line (WAN connection).
In simple words: Local units use LAN/MAN with optical fiber, and long distance to Delhi uses satellite or leased lines.

Exam Tip: For high-speed communication over several kilometers within a city, Optical Fiber is always the preferred choice over standard copper Ethernet cables.

1 and 2 Marks Questions

Q(1) What do you mean by a computer network?
Answer: Computer network is an interconnection of autonomous computers connected together using transmission media.
In simple words: A network is a group of connected computers that share information.

Exam Tip: Mention both interconnected computers and transmission media for full marks.

Q(2) What is the need for networking the computers?
Answer: 1. Sharing of Information, 2. Reliability, 3. Reduces cost, 4. Time saving.
In simple words: Networks let us share files, save money, and work faster.

Exam Tip: List at least 3 points clearly in examinations.

Q(3) What is the full form of ARPANET?
Answer: Advanced Research Projects Agency Network.
In simple words: ARPANET was the first computer network created by the US government.

Q(4) What are various data transmission modes?
Answer: There are three modes of data transmission: Simplex, Half-duplex, and Full-duplex.
In simple words: Data can travel one way only, both ways one at a time, or both ways at the same time.

Exam Tip: Memorize the three communication directions: Simplex, Half-Duplex, Full-Duplex.

Q(5) What is the difference between Simplex and half duplex transmission?
Answer: In simplex transmission mode, data can be transferred in only one direction, whereas in half-duplex transmission mode, data can be transmitted in both directions but only one direction at a time.
In simple words: Simplex is like a keyboard to computer; half-duplex is like a walkie-talkie.

Exam Tip: Give a practical example like radio broadcast (simplex) vs walkie-talkie (half-duplex).

Q(6) What do you mean by MODEM?
Answer: MODEM stands for MOdulator-DEModulator. It is a device that can convert an analog signal into a digital signal and vice versa.
In simple words: A modem translates computer digital signals into phone line analog signals and back.

Q(7) Define the term Bandwidth.
Answer: Bandwidth is the range of frequencies available for the transmission of data. Wider the bandwidth of a communication channel, the more data it can transmit in a given period of time.
In simple words: Bandwidth is the data-carrying capacity of a communication channel.

Q(8) What are various types of transmission media?
Answer: There are two broad categories of transmission media: Guided media (cables) and Unguided media (wireless).
In simple words: Transmission media is either wired or wireless.

Q(9) Explain in brief the advantages and disadvantages of Twisted pair Cable.
Answer:
Advantages:
- Inexpensive
- Often available in existing phone systems
- Well tested and easy to get
Disadvantages:
- Susceptible to noise (sound, energy, etc.)
- Not as durable as coaxial cable
- Does not support very high speed over long distances
In simple words: Twisted pair is cheap and common, but prone to noise and slow over long distances.

Q(10) What do you mean by communication protocol?
Answer: A protocol is a set of rules to enable computers to connect with one another and to exchange information with minimum possible error.
In simple words: Protocols are the rulebook for computers talking to each other.

Q(11) List various functions of Communication protocol.
Answer: Data sequencing, Data formatting, Flow control, Error control, Connection establishment and termination, and Data security.
In simple words: Protocols manage how data is broken down, checked for errors, and securely delivered.

Q(12) List commonly used protocols.
Answer: HTTP, TCP/IP, FTP, SLIP, PPP, SMTP, POP, ICMP.
In simple words: Common protocols include HTTP for web browsing and FTP for file transfers.

Q(13) What are the main functions of TCP?
Answer: The TCP does the following activities:
- It breaks the data into packets.
- Verifies that all the packets arrived at the destination.
- Reassembles the data in correct order.
In simple words: TCP chops data into packets, checks delivery, and puts them back together.

Q(14) What do you mean by network topology?
Answer: Topology is the geometric arrangement in which the nodes/computers are interconnected together.
In simple words: Topology is how computers are physically or logically laid out in a network.

Q(15) List various types of Networks.
Answer: LAN, MAN, WAN (also PAN).
In simple words: Networks range from small room LANs to worldwide WANs.

Q(16) Give names of various networking topologies in LAN.
Answer: 1. Star Topology, 2. Ring Topology, 3. Bus Topology, 4. Mesh Topology, 5. Tree Topology.
In simple words: Common LAN layouts are Star, Bus, Ring, Mesh, and Tree.

Q(17) Write two advantages and two disadvantages of STAR topology.
Answer:
Advantages:
- It is easy to modify and add new computers without disturbing the rest of the network.
- Troubleshooting a star topology network is easy.
Disadvantages:
- All nodes depend on the central hub; failure of the hub shuts down the whole system.
- Long cable length is required.
In simple words: Star topology is easy to fix, but if the central hub fails, everything stops.

Q(18) What is NFS?
Answer: NFS stands for Network File System. NFS is a protocol that allows a set of computers to access each other's files over a network.
In simple words: NFS lets computers share and access files stored on other network machines.

Q.1 What is protocol? How many types of protocols are there?
Answer: A specific set of communication rules and instructions that computers follow to communicate is called a protocol. Examples include PPP, HTTP, SLIP, FTP, and TCP/IP.
In simple words: Protocols are standard rules for network communication.

Q.2 What is the difference between Networking and Remote Networking?
Answer: Local networking is used in offices or local places using LAN or Internet connectivity, whereas remote networking uses terminal services to communicate with distant users across a wide area network (WAN).
In simple words: Local networking is inside a building; remote networking connects distant computers via WAN.

Q.3 What is point-to-point protocol?
Answer: Point-to-Point Protocol (PPP) is a communication protocol used to establish a direct connection between two nodes, commonly used to connect a computer to remote networking services like Internet Service Providers using a phone line.
In simple words: PPP establishes a direct, dedicated connection between two networking devices.

Q.4 How gateway is different from router?
Answer: A router forwards packets between similar networks based on network layer information. A gateway operates at upper levels of the OSI model and performs application layer protocol conversion to connect two completely different network architectures.
In simple words: Routers connect similar networks, while gateways translate between completely different networks.

Q.5 What is the role of network administrator?
Answer: Basic tasks for a network administrator include:
- Setting up and configuring network hardware and software.
- Installing and configuring network media and connections.
- Connecting user nodes and peripherals.
- Adding and removing users and managing user accounts.
- Ensuring network security.
- Providing user training on network resources.
In simple words: Network admins manage hardware, user accounts, security, and network maintenance.

Q.6 What is the difference between baseband and broadband transmission?
Answer: Baseband is a bi-directional digital transmission where the entire cable bandwidth is consumed by a single signal for short distances. Broadband is a unidirectional analog transmission using multiple frequencies to send multiple signals simultaneously over long distances.
In simple words: Baseband sends one digital signal at a time; broadband sends multiple signals on different frequencies.

Q.7 What are the difference between domain and workgroup?
Answer:
A domain uses one or more servers, allows users with an account on the domain to log on to any computer in the domain, supports 100+ computers, and can span different local networks. A workgroup consists of peer computers where each computer has its own set of local accounts, typically limited to 20-30 computers on the same local network.
In simple words: Domains have central servers and shared logins; workgroups are peer-to-peer networks.

Q.8 What is the differences between POP3 and IMAP Mail Server?
Answer: IMAP is a standard protocol where e-mails are stored on the server and accessed from local clients. POP3 (Post Office Protocol 3) downloads mail to the client computer and removes it from the server.
In simple words: IMAP keeps emails on the server; POP3 downloads them to your device and deletes them from the server.

Q.9 Name different layer of the ISO OSI Model.
Answer: The ISO OSI Model has seven layers:
1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer
In simple words: The OSI model divides network communication into 7 distinct functional layers.

Q.10 What is client server architecture?
Answer: A network architecture where a designated node with a well-known, fixed address provides services to the network (known as the server), while other nodes that consume those services are called clients.
In simple words: Clients request services, and servers provide them.

Q.11 What is FDM? Give example.
Answer: FDM (Frequency Division Multiplexing) is used in analog transmission over short distances where the total bandwidth is divided into non-overlapping frequency sub-channels. Example: Receiving various radio stations on a radio receiver.
In simple words: FDM splits bandwidth into multiple channels, like different radio stations.

Q.12 Describe the following in brief: i) MOSAIC ii) USENET iii) WAIS
Answer:
i) MOSAIC: An early web browser developed at the University of Illinois with a simple window interface and hypertext links.
ii) USENET: A worldwide discussion system where users share information through special newsgroups.
iii) WAIS: Wide Area Information Server, used for indexing and searching documents across networks.
In simple words: Mosaic was an early browser, Usenet was for discussion groups, and WAIS searched databases.