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Solutions for Computer Science, Class 12, CBSE
Assertion. A modem is a communication device that works on the principle of converting digital data to analog data and vice versa.
Reason. Modulation is a process of converting digital data to analog form and Demodulation is a process of converting analog data to digital form.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
Modem is a communication device that works on the process of modulation/demodulation. In modulation, digital data of the sender computer is converted in analog form to travel over the telephone lines to the target computer. In demodulation, received analog data is converted back to digital form for the target computer.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
A hub can also act as an amplifier at times. Hubs can function as either passive or active devices. Active hubs electrically amplify the signal as it moves from one connected device to another. While passive hubs allow the signal to pass from one computer to another without any change.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
A repeater is not like an amplifier because a repeater not only amplifies the signal but also performs signal regeneration. When a signal weakens over long distances, the repeater collects the inbound packet and then retransmits it as if it were originating from the source station. This process effectively removes noise.
(d)
Assertion is false but Reason is true.
Explanation
A router is a network device that forwards data from one network to another using logical addresses. A router works like a bridge but can handle different protocols. On the other hand, a bridge is a device that links two networks together using physical addresses and can handle networks that follow the same protocols. Hence, a router and a bridge are different.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
Both IMAP and POP3 protocols are used with email accessing. IMAP (Internet Message Access Protocol) is a standard protocol for accessing e-mail from local server. Whereas POP3 (Post Office Protocol 3) provides a simple, standardized way for users to access mailboxes and download messages to their computers.
(b)
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation
Both hubs and switches are used to connect multiple devices in a network. Hence they are replaceable with each other. Switches offer more efficient data transmission compared to hubs because they can direct data specifically to the intended device connected to it, unlike a hub that just sends data to all connected devices. This makes a switch more efficient for managing network traffic. Therefore, a hub is a broadcast device, a switch is a unicast device.
Assertion. Internet Protocol allows the voice data transmission along with other data over packet-switched networks.
Reason. VoIP (Voice over Internet Protocol) enables voice communication over the Internet through the compression of voice into the data packets being transmitted.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
VoIP (Voice over Internet Protocol) is a technology that enables voice communications over the internet through the compression of voice into data packets that can be efficiently transmitted over data networks and then converted back into voice at the other end. Internet Protocol (IP) allows for voice transmission along with other data over packet-switched networks.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
Both hackers and crackers do the same thing, i.e., hack a system but with different intentions. Hackers are technically sound people who hack devices and systems with good intentions, such as to find the security lapses of a system, in order to rectify it or for obtaining more knowledge out of it. But crackers are technically sound people with malicious intentions who hack a system by breaking into it and violating it for some bad motives.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
Malware is an umbrella term for any piece of software that has malicious intent. Viruses, Worms, Trojans, Adware, Spyware are all types of malware.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
A trojan horse is code hidden in a useful looking program such as a game or spreadsheet that looks safe to run but has hidden side effects. When the program is run, it seems to function as the user expects, but in actuality it is destroying, damaging, or altering information in the background. Therefore, a useful looking program may damage data.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
Spyware are the software that stealthily attach with computer software such as a web browser and stealthily collect information about user's activities such as passwords, pins, banking information etc. Hence, spyware may not directly damage data, but they track data about user and sell it to others hampering user's data privacy.
(a)
Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
When some one listens to a conversation that they are not part of, it is eavesdropping. Formally we can say that the intentional interception of someone else's data (such as email, login-id, password, credit card info etc.) as it passes through a user's computer to server or vice-versa is called eavesdropping. Data may be stolen through eavesdropping.
Modem stands for Modulator DEModulator. It is a computer peripheral device that allows us to connect and communicate with other computers via telephone lines.
Modems come in two varieties :
A bridge is a device that links two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. Bridges can handle networks that follow same protocols.
Gateways relay packets among networks that have different protocols (e.g., between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it.
A repeater is a network device that amplifies and restores signals for long-distance transmission. It is used in long network lines, which exceed the maximum rated distance for a single run.
Over distance, the cables connecting a network lose the signal transmitted. Repeaters are installed along the way in the network to ensure that data packets reach their destination without any degradation of the message.
File Transfer Protocol is a standard for the exchange of files across internet. Files of any type can be transferred, whether the file is an ASCII or binary file. They can be transferred to any system on the Internet provided that permissions are set accordingly.
The main objectives of FTP are as follows:
A protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
Some commonly used protocols are as follows:
TCP/IP (Transmission Control Protocol/Internet Protocol) is the base communication protocol of the Internet. IP part of TCP/IP uses numeric IP addresses to join network segments and TCP part of TCP/IP provides reliable delivery of messages between networked computers.
HTTP (Hypertext Transfer Protocol) is the set ot rules for transferring hypertext, like text, graphic, image, sound, video etc., on World Wide Web.
Mobile communication means that the computing device is not continuously connected to the base or central network. Mobile computing does not necessarily require wireless communication. It may not require communication between devices at all.
Wireless communication refers to the method of transferring information between a computing device and a data source without a physical connection.
GSM refers to Global System for Mobile communications. It is a technique that uses narrowband TDMA (Time Division Multiple Access), which allows eight simultaneous calls on the same radio frequency. TDMA technology uses time-division multiplexing (TDM) and divides a radio frequency into time slots and then allocates these slots to multiple calls thereby supporting multiple, simultaneous data channels.
Comparison between 3G, 4G and 5G networks is given below:
3G (Third Generation) | 4G (Fourth Generation) | 5G (Fifth Generation) | |
---|---|---|---|
Bandwidth | 2 mbps | 200 mbps | >1 gbps |
Technology | Broadband/CDMA/IP technology | unified IP and seamless combo of LAN/WAN/WLAN/PAN | 4G + WWW |
Services | Integrated high quality audio, video and data | Data + Voice converged over IP | Better quality voice with super high speed data transmission |
Switching | Packet network | Internet | Internet |
Voice over Internet Protocol or VoIP is a technology that enables voice communications over the Internet through the compression of voice into data packets that can be efficiently transmitted over data networks and then converted back into voice at the other end.
Two most common ways to connect to Internet wirelessly are :
Remote login is the process of accessing a network from a remote place without actually being at the actual place of working.
Telnet is an Internet utility that lets us log onto remote computer systems. A Telnet program gives a character-based terminal window on another system.
HTML stands for Hyper Text Markup Language. It is a markup language, which is used to define the layout and attributes of a World Wide Web (WWW) document as well as to create links between Web pages.
It is created for enabling the user to structure sections, paragraphs, headlines, links for applications and website pages, and block quotes. It is used for displaying data on the internet and it helps in making the web pages look attractive.
A URL (Uniform Resource Locator) specifies the distinct address for each resource on the Internet. Each website on the internet has a unique URL. The format of URL is as follows:
type://address/path
where, 'type' specifies the type of server in which the file is located, 'address' is the address of server, and 'path' tells the location of file on the server.
An example of URL is http://encycle.msn.com/getinfo/styles.asp
The World Wide Web (WWW) is a set of protocols that allows us to access any document on the internet through a naming system based on uniform resource locators (URLs).
The process of creating and embedding scripts in a web page is known as web-scripting. A script or a computer-script is a list of commands that are embedded in a web-page normally and are interpreted and executed by a certain program or scripting engine.
Hacking is the unauthorized access of a computer system and networks. Whoever with the intent to cause or knowing that he is likely to cause wrongful loss or damage to the public or any person destroys or deletes or alters any information residing in a computer resource or diminishes its value or utility or affects it injuriously by any means is said to commit hacking.
Cracking refers to breaking into secure systems with the purpose of stealing and corrupting data.
Cracking and hacking have different intentions behind them. Cracking is done with malicious intentions whereas hacking is done for gaining knowledge about computer systems and possibly using this knowledge to find lack in security or for playful pranks.
The various network devices are as follows :
Modem — Modem stands for Modulator Demodulator. It is a computer peripheral device that allows us to connect and communicate with other computers via telephone lines. Modems come in two varieties :
RJ-45 — RJ-45 refers to Registered Jack-45. It is an eight-wire connector, which is commonly used to connect computers on the local area networks (LANs), especially Ethernets.
NIC (Network Interface Card) — The network interface card is a device that is attached to each of the workstations and the server, and helps the workstation establish all the important connections with the network. Each NIC that is attached to a workstation has a unique number identifying it, which is known as the node address. The NIC manufacturer assigns a unique physical address (48 bits) to each NIC card, which is known as MAC address.
Ethernet Card — Ethernet Card is a type of Network Interface card, which is specific to Ethernet technology. An Ethernet card contains connections for either coaxial or twisted pair cables or both.
Hub — A hub is a networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together.
Switch — A switch is a device that is used to segment networks into different sub-networks, called subnets or LAN segments. A switch is responsible for filtering i.e., transforming data in a specific way and for forwarding packets between LAN segments.
Repeater — A repeater is a network device that amplifies and restores signals for long-distance transmission.
Bridge — A bridge is a device that links two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. Bridges can handle networks that follow same protocols.
Router — A router is a network device that forwards data from one network to another. A router works like a bridge but can handle different protocols.
Gateway — A gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely different structures.
WiFi Card — A WiFi card is either an internal or external Local Area Network adapter with a built-in wireless radio and antenna.
The network protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
The various network protocols are as follows :
HTTP (Hypertext Transfer Protocol) — HTTP is the set of rules for transferring hypertext on world wide web. It is an application level protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems. It is a generic, stateless, object-oriented protocol which can be used for many tasks, such as name servers and distributed object management systems. The HTTP protocol consists of two fairly distinct items : the set of requests from browsers to servers and the set of responses going back to the other way.
HTTPS (Hypertext Transfer Protocol Secure) — HTTPS is a secure version of HTTP protocol that uses the SSL/TLS protocol for encryption and authentication. HTTPS sends the data in encrypted form to make the transmission secure.
FTP (File Transfer Protocol) — FTP is a standard for the exchange of files across internet. Files of any type can be transferred through it. FTP is also the name of a program or command. The objectives of FTP are to encourage indirect or implicit use of remote computers, to shield a user from variations in file storage systems among hosts.
TCP/IP (Transmission Control Protocol/Internet Protocol) — It is the base communication protocol of the Internet. TCP is responsible for full-fledged data connectivity and transmitting the data end-to-end by providing other functions, including addressing, mapping and acknowledgement. IP is responsible for obtaining the address of the computer/device to which data is being sent.
SLIP/PPP — SLIP (Serial Line IP) was the first protocol for relaying IP packets over dial-up lines. It defines an encapsulation mechanism, but little else. There is no dynamic address assignment, link testing, or multiplexing different protocols over a single link.
PPP (Point to Point Protocols) is the internet standard for transmission of IP packets over serial lines. It is a data link protocol commonly used in establishing a direct connection between two networking nodes and enabling IP communication over this direct connection.
Protocols used by email — The protocols mainly used with email accessing are IMAP, POP3, SMTP and HTTP.
Wireless computing refers to the method of transferring information between computing devices without a physical connection. For example, transmission between a personal data assistant (PDA), and a data source. Not all wireless communications technologies are mobile. Wireless communication is simply data communication without the use of landlines. The computing device is continuously connected to the base network.
Mobile computing means that the computing device is not continuously connected to the base or central network. Mobile computing does not necessarily require wireless communication. It may not require communication between devices at all.
Various techniques used for wireless and mobile computing are as follows:
Network security refers to making sure that only legal or authorized users and programs gain access to information resources like databases. Also, certain control mechanisms are setup to ensure that properly authenticated users get access only to those resources that they are entitled to use.
Network security is very important because data travels through a network. Protection of data and its secure transmission is only possible if methods are employed to secure the network from various threats like physical/software security holes, inconsistent usage holes, hacking, cracking, etc.
Network security can be achieved through the following protective measures:
"New York Avenue" is planning to expand their network in India, starting with two cities in India to provide infrastructure for distribution of their canned products. The company has planned to set up their main offices in Ahmedabad, at three different locations and have named their offices as "Work Office", "Factory" and "Back Office". The company has its Corporate Unit in Delhi. A rough layout of the same is as shown below:
Approximate distance between these offices is as follows :
From | To | Distance |
---|---|---|
Work Office | Back Office | 110 m |
Work Office | Factory | 14 km |
Work Office | Corporate Office | 1280 km |
Back Office | Factory | 13 km |
In continuation of the above, the company experts have planned to install the following number of computers in each of their offices :
Work Office | 200 |
Back Office | 115 |
Factory | 67 |
Corporate | 75 |
(i) Suggest the kind of network required (out of LAN, MAN, WAN) for connecting each of the following offices:
(ii) Which one of the following devices will you suggest for connecting all the computers within each of their office units ?
(iii) Which of the following communication media, you will suggest to be procured by the company for connecting their local offices in Ahmedabad for very effective (High Speed) communication ?
(iv) Suggest a cable/wiring layout for connecting the company's local office units located in Ahmedabad. Also, suggest an effective method/technology for connecting the company's office unit located in Delhi.
(v) Which one of the following devices will you suggest for connecting all the computers within each of their offices ?
(i) The kind of network required are:
(ii) Switch/Hub
(iii) Optical Fibre
(iv) Wiring layout for connecting the company's local office units located in Ahmedabad is shown below:
Work office - Factory - Back office
An effective method/technology for connecting the company's office unit located in Delhi is through satellite.
(v) Switch/Hub
Global Village Enterprises has following four buildings in Hyderabad city :
Computers in each building are networked but buildings are not networked so far. The company has now decided to connect buildings also.
(a) Suggest a cable layout for these buildings.
(b) In each of the buildings, the management wants that each LAN segment gets a dedicated bandwidth i.e., bandwidth must not be shared. How can this be achieved ?
(c) The company also wants to make available shared Internet access for each of the buildings. How can this be achieved ?
(d) The company wants to link its head office in GV1 building to its another office in Japan.
(a) The cable layout for these buildings is given below:
GV1 - GV2 - GV3 - GV4
(b) A dedicated bandwidth can be achieved by using switches as it does not share the media/bandwidth among all its connected computers.
(c) Switches will be able to provide shared Internet access for each of the buildings.
(d) To connect head office in GV1 building to Japan office:
Satellite transmission would be appropriate.
It will be a WAN connection.
"China Middleton Fashion" is planning to expand their network in India, starting with two cities in India to provide infrastructure for distribution of their product. The company has planned to setup their main office in Chennai at three different locations and have named their offices as "Production Unit", "Finance Unit" and "Media Unit". The company has its corporate unit in Delhi. A rough layout of the same is shown on the right :
Approximate distance between these Units is as follows :
From | To | Distance |
---|---|---|
Production Unit | Finance Unit | 70 m |
Production Unit | Media Unit | 15 km |
Production Unit | Corporate Unit | 2112 km |
Finance Unit | Media Unit | 15 km |
In continuation of the above, the company experts have planned to install the following number of computers in each of their offices :
Production Unit | 150 |
Finance Unit | 35 |
Media Unit | 10 |
Corporate Unit | 30 |
(i) Suggest the kind of network required (out of LAN, MAN, WAN) for connecting each of the following office units :
(ii) Which one of the following devices will you suggest for connecting all the computers within each of their office units ?
(iii) Which of the following communication media, you will suggest to be procured by the company for connecting their local office units in Chennai for very effective (High Speed) communication ?
(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.
(i) The network used to connect :
(ii) Switch/Hub
(iii) Optical Fibre
(iv) Two possible cable/wiring layouts for connecting the company's local office units located in Chennai are given below:
Production Unit - Finance Unit - Media Unit
Media Unit - Production Unit - Finance Unit
Satellite links can be established for connecting the company's office unit located in Delhi.
"Bhartiya Connectivity Association" is planning to spread their offices in four major cities in India to provide regional IT infrastructure support in the field of Education & Culture. The company has planned to setup their head office in New Delhi in three locations and have named their New Delhi offices as "Front Office", "Back Office" and "Work Office". The company has three more regional offices as "South Office", "East Office" and "West Office" located in other three major cities of India. A rough layout of the same is as follows :
Approximate distances between these offices as per network survey team is as follows :
Place From | Place To | Distance |
---|---|---|
Back Office | Front Office | 10 km |
Back Office | Work Office | 70 m |
Back Office | East Office | 1291 km |
Back Office | West Office | 790 km |
Back Office | South Office | 1952 km |
In continuation of the above, the company experts have planned to install the following number of computers in each of their offices :
Back Office | 100 |
Front Office | 20 |
Work Office | 50 |
East Office | 50 |
West Office | 50 |
South Office | 50 |
(i) Suggest network type (out of LAN, MAN, WAN) for connecting each of the following offices :
(ii) Which device you will suggest to be produced by the company for connecting all the computers with in each of their offices out of the following devices ?
(iii) Which of the following communication medium, you will suggest to be procured by the company for connecting their local offices in New Delhi for very effective and fast communication ?
(iv) Suggest a cable/wiring layout for connecting the company's local offices located in New Delhi. Also, suggest an effective method/technology for connecting the company's regional offices-"East Office", "West Office" and "South Office" with offices located in New Delhi.
(i) The network types for connecting the offices :
(ii) Switch/Hub
(iii) Optical Fibre
(iv) A cable/wiring layout for connecting the company's local offices located in New Delhi is given below:
Front office - Back office - Work office
Satellite links can be established for connecting the company's regional offices-"East Office", "West Office" and "South Office" with offices located in New Delhi.
INDIAN PUBLIC SCHOOL in Darjeeling is setting up the network between its different wings. There are 4 wings named as SENIORS(S), JUNIOR(J), ADMIN(A) and HOSTEL(H).
Distance between various wings are given below :
Wing A to Wing S | 100 m |
Wing A to Wing J | 200 m |
Wing A to Wing H | 400 m |
Wing S to Wing J | 300 m |
Wing S to Wing H | 100 m |
Wing J to Wing H | 450 m |
Number of Computers
Wing A | 10 |
Wing S | 200 |
Wing J | 100 |
Wing H | 50 |
(i) Suggest a suitable Topology for networking the computer of all wings.
(ii) Name the wing where the server is to be installed. Justify your answer.
(iii) Suggest the placement of Hub/Switch in the network.
(iv) Mention an economic technology to provide internet accessibility to all wings.
(i) Star Topology can be used to network the computer of all wings.
(ii) The server should be installed in Wing S, as Wing S has maximum number of computers and installing the server in this wing will help to keep maximum percentage of the network traffic local.
(iii) Hub/ Switch will be required in all the Wings.
(iv) The economic way to provide internet accessibility to all wings is to use the proxy server at wing S and connect to the internet through a dial-up network.
Eduminds University of India is starting its first campus in a small town Parampur of Central India with its center admission office in Delhi. The university has 3 major buildings comprising of Admin Building, Academic Building and Research Building in the 5 KM area Campus.
As a network expert, you need to suggest the network plan as per (1) to (4), keeping in mind the distances and other given parameters.
Expected Wire distances between various locations :
Research Building to Admin Building | 90 m |
Research Building to Academic Building | 80 m |
Academic Building to Admin Building | 15 m |
Delhi Admission Office to Parampur Campus | 1450 km |
Expected number of Computers to be installed at various locations in the University are as follows :
Research Building | 20 |
Academic Building | 150 |
Admin Building | 30 |
Delhi Admission Office | 5 |
(i) Suggest the authorities, the cable layout amongst various buildings inside the university campus for connecting the buildings.
(ii) Suggest the most suitable place (i.e., building) to house the server of this organisation, with a suitable reason.
(iii) Suggest an efficient device from the following to be installed in each of the buildings to connect all the computers :
(iv) Suggest the most suitable (very high speed) service to provide data connectivity between Admission Building located in Delhi and the campus located in Parampur from the following options.
(i) The cable layout amongst various buildings inside the university campus for connecting the buildings is given below:
Research building - Academic building - Admin building
(ii) The most suitable place to house the server is Academic Building as it has maximum number of computers. Thus, it decreases the cabling cost and keeps the maximum traffic local.
(iii) Switch can be installed in each of building to connect all the computers.
(iv) Satellite connection is the most suitable service to provide data connectivity between Admission Building located in Delhi and the campus located in Parampur.
Great Studies University is setting up its Academic schools at Sunder Nagar and planning to set up a network. The university has 3 academic schools and one administration center as shown in the diagram below:
Center to center distances between various buildings are :
Law School to Business School | 60 m |
Law School to Technology School | 90 m |
Law School to Admin Center | 115 m |
Business School to Technology School | 40 m |
Business School to Admin Center | 45 m |
Technology School to Admin Center | 25 m |
No. of Computers in each of the buildings are :
Law School | 25 |
Technology School | 50 |
Admin Center | 125 |
Business School | 35 |
(a) Suggest the most suitable place (i.e., Schools/Center) to install the server of this university with a suitable reason.
(b) Suggest an ideal layout for connecting these Schools/center for a wired connectivity.
(c) Which device you will suggest to be placed/installed in each of these Schools/center to efficiently connect all the computers within these Schools/center ?
(d) The university is planning to connect its admission office in the closest big city, which is more than 350 km from the university. Which type of network out of LAN, MAN or WAN will be formed ? Justify your answer.
(a) The most suitable place to install the server is the Admin Center as it houses the maximum number of computers. Thus, reducing the cable cost and keeping most of the traffic local.
(b) An ideal layout for connecting these Schools/center for a wired connectivity is given below:
Law School - Business School - Technology School - Admin Center
(c) A hub/switch can be installed in each of these Schools/center to efficiently connect all the computers within these Schools/center.
(d) WAN will be formed as the distance between the admission office and the university is 350 km, which is more than the range of LAN and MAN.
Expertia Professional Global (EPG) is an online corporate training provider company for IT related courses. The company is setting up their new campus in Mumbai. You as a network expert have to study the physical locations of various buildings and the number of computers to be installed. In the planning phase, provide the best possible answers for the queries (i) to (iv) raised by them.
Building to Building Distance (in m) :
From | To | Distance |
---|---|---|
Admin. Building | Finance Building | 60 |
Admin. Building | Faculty Studio Building | 120 |
Finance Building | Faculty Studio Building | 70 |
Computers to be Installed in each Building :
Buildings | Computers |
---|---|
Admin. Building | 20 |
Finance Building | 40 |
Faculty Studio Building | 120 |
(i) Suggest the most appropriate building, where EPG should plan to install the server.
(ii) Suggest the most appropriate building cable layout to connect all three buildings for efficient communication.
(iii) Which type of network out of the following is formed by connecting the computers of the buildings?
(iv) Which wireless channel out of the following should be opted by EPG to connect to students of all over the world ?
(i) EPG should install the server in Faculty Studio Building as it houses the maximum number of computers. Thus, it will reduce cable cost and keep maximum traffic local.
(ii) The most appropriate building cable layout to connect all three buildings for efficient communication is given below:
Administrative Building - Finance Building - Faculty Studio Building
(iii) LAN network is formed as the distance between the three buildings is less than 1 km.
(iv) Satellite communication should be opted by EPG to connect to students of all over the world.
Gateway
Reason — A gateway is a network device that connects dissimilar networks, establishes an intelligent connection between a local network and external networks with completely different structures.
Router
Reason — Based on a network road map called a route table, routers can help ensure that packets are travelling the most efficient paths to their destinations.
Modulator Demodulator
Reason — "Modulator Demodulator" describes the function of a MODEM, which is to modulate digital data from the sender computer into analog form to travel over the telephone lines to the target computer and to demodulate received analog data into digital form for the target computer.
Hub
Reason — A hub is a networking device with multiple ports that is used for connecting multiple computers or segments of a LAN together. It broadcasts messages to all nodes in the network, but only the target node accepts the message while others ignore it.
Switch
Reason — A switch is responsible for filtering data packets and only sending them to the devices that require the data. This is because a switch is a device that is used to segment networks into different subnetworks called subnets or LAN segments.
Switch
Reason — Switches are more intelligent when sending data packets compared to routers and modems. A switch is responsible for filtering data packets and only sending them to the devices that require the data. This is because a switch is a device used to segment networks into different subnetworks called subnets or LAN segments.
Hub
Reason — A hub is a networking device with multiple ports that is used for connecting multiple computers or segments of a LAN together. It broadcasts messages to all nodes in the network, but only the target node accepts the message while others ignore it.
TCP/IP
Reason — TCP/IP is the main communication protocol of the Internet. It is responsible for providing full-fledged data connectivity and transmitting data end-to-end. Additionally, TCP/IP performs other functions such as addressing, mapping, and acknowledgment.
Web based email programs
Reason — IMAP (Internet Message Access Protocol) is a standard protocol for accessing email from local server. It is a client/server protocol in which email is received and held for the user by Internet server.
The difference between IMAP and POP protocols:
POP allows to download emails once the user accesses the email account while IMAP doesn't
Reason — In the POP (Post Office Protocol) protocol, all email messages are downloaded from the mail server to the user's local computer. On the other hand, in the IMAP (Internet Message Access Protocol) protocol, email messages are stored on the server, and only when the user requests to read a specific email message, it is downloaded from the server to the user's device.
sends and receives messages in encrypted form
Reason — HTTPS (Hypertext Transfer Protocol Secure) is a secure version of the HTTP protocol that uses the SSL/TLS protocol for encryption and authentication. HTTPS sends and receives the data in encrypted form to make the transmission secure.
All of these
Reason — A network protocol encompasses all of the options listed. It is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
HTTPS
Reason — The image is a padlock sign. The padlock symbol in the address bar typically indicates a secure connection using HTTPS (Hypertext Transfer Protocol Secure). HTTPS is a secure version of HTTP protocol that uses encryption to ensure secure communication over the internet.
Accessing emails
Reason — The POP3 (Post Office Protocol 3) protocol provides a simple, standardized way for users to access mailboxes and download emails to their computers.
Sending emails from one server to another
Reason — The SMTP (Simple Mail Transfer Protocol) protocol is used by the Mail Transfer Agent (MTA) to deliver sent email to the recipients's mail server. This protocol can only be used to send emails, not to receive them.
IMAP
Reason — IMAP (Internet Message Access Protocol) is a standard protocol for accessing email form local server. On the other hand, FTP, HTTP, and HTTPS are network protocols used for the exchange of files across the internet. Therefore, IMAP is the odd one out.
Assigning addresses to the packets
Reason — IP (Internet Protocol) assigns addresses to the packets to specify the source and destination of the data being transmitted over the network.
Assigning addresses to the packets
Reason — IP (Internet Protocol) assigns addresses to the packets to specify the source and destination of the data being transmitted over the network.
HTTP
Reason — HTTP (Hypertext Transfer Protocol) is the set of rules for transferring hypertext on WWW (World Wide Web). On the other hand, GPRS (General Packet Radio Service), GSM (Global System for Mobile), and 5G are all mobile communication technologies.
Web 3.0
Reason — Web 3.0 aims at combining new technologies like artificial intelligence (AI), machine learning (ML), and blockchain etc. so as to power intelligent apps over the internet.
Firewall
Reason — A system designed to prevent unauthorized access to or from a private network is called Firewall. Firewalls can be implemented in both hardware and software, or a combination of both.
Trojan horse
Reason — A Trojan Horse is code hidden in a useful looking program such as a game or spreadsheet that looks safe to run but has hidden side effects.
VoIP
Reason — VoIP is a technology designed to deliver both voice and multimedia communications over the internet protocol which makes it an ideal choice for an audio-visual chat with an expert sitting in a far-away place to fix-up a technical issue.
VoIP
Reason — VoIP (Voice over Internet Protocol) is a communication methodology designed to deliver both voice and multimedia communications over Internet protocol.
Tarini Wadhawa is in India and she is interested in communicating with her uncle in Australia. She wants to show one of her own designed gadgets to him and also wants to demonstrate its working without physically going to Australia. Which protocol out of the following will be ideal for the same ?
VoIP
Reason — VoIP (Voice over Internet Protocol) allows for real-time audio and video communication over the internet, making it an ideal choice for Tarini to communicate with her uncle in Australia and demonstrate her gadget's functionality without physically going to Australia.
Which of the following statements correctly explains the term Firewall in context of Computer Network Society ?
A device/software that controls incoming and outgoing network traffic.
Reason — The system designed to prevent unauthorized access to or from a private network is called Firewall.
Modem stands for Modulator Demodulator. It is a computer peripheral that connects a workstation to other work-stations via telephone lines and facilitates communications. It converts digital signals to audio frequency tones which are in the frequency range that the telephone lines can transmit and it can also convert transmitted tones back to digital information.
A hub is networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together. Hubs are of two types:
A switch is a device that is used to segment networks into different sub-networks, called subnets or LAN segments to prevent traffic overloading.
A switch is responsible for filtering i.e., transforming data in a specific way and for forwarding packets between LAN segments. To insulate the transmission from the other ports, the switch establishes a temporary connection between source and destination and then terminates the connection once the conversation is done.
A repeater is a network device that amplifies and restores signals for long-distance transmission. It is used in long network lines, which exceed the maximum rated distance for a single run.
Over distance, the cables connecting a network lose the signal transmitted. Repeaters are installed along the way in the network to ensure that data packets reach their destination without any degradation of the message.
A router is a network device that forwards data from one network to another. A router works like a bridge but can handle different protocols. Based on a network road map called a routing table, routers can help ensure that packets are travelling the most efficient paths to their destinations. If a link between two routers fails, the sending router can determine an alternate route to keep traffic moving.
A bridge is a device that links two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. Bridges can handle networks that follow same protocols.
A gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely different structures.
In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In homes, the gateway is the ISP that connects the user to the Internet.
A communication protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
The reason that the Internet works at all is that every computer connected to it uses the same set of rules for communication. The communication protocol used by Internet is TCP/IP.
HTTP (Hypertext Transfer Protocol) is the set ot rules for transferring hypertext, like text, graphic, image, sound, video etc., on World Wide Web.
It is an application-level protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems. It is a generic, stateless, object-oriented protocol. A feature of HTTP is the typing of data representation, allowing systems to be built independently of the data being transferred.
HTTP is also used as a generic protocol for communication between user agents and proxies/gateways to other Internet protocols. The HTTP protocol consists of two fairly distinct items : the set of requests from browsers to servers and the set of responses going back to the other way.
TCP/IP is the base communication protocol of the Internet. IP part of TCP/IP uses numeric IP addresses to join network segments and TCP part of TCP/IP provides reliable delivery of messages between networked computers.
TCP is responsible for making sure that the commands get through to the other end. It keeps track of what is sent, and retransmits anything that did not get through.
TCP/IP applications use the following four layers:
File Transfer Protocol is a standard for the exchange of files across internet. Files of any type can be transferred, whether the file is an ASCII or binary file. They can be transferred to any system on the Internet provided that permissions are set accordingly.
The main objectives of FTP are as follows:
Telnet enables users to remotely access computer systems. Essentially, a Telnet program provides a character-based terminal window on another system. Upon connection, users receive a login prompt on that system. If access is permitted, users can operate on that system, much like they would if physically present next to it.
The advantages of E-mail are as follows:
The disadvantages of E-mail are as follows:
A two-way videophone conversation among multiple participants is called Video Conferencing.
To make use of video conferencing, one must have a multimedia PC with a camera and video compression hardware, access to Internet over an ordinary telephone line, and videophone software.
A Web Browser is a WWW client that navigates through the World Wide Web and displays web pages. For example, Internet Explorer, Google Chrome etc.
A Web Server is a WWW server that responds to the requests made by web browsers.
The World Wide Web (WWW) is based upon clients and servers. A web browser sends request to the web server and web server responds to the request made by web browser and fulfills the request accordingly. Hence, the web browser acts as a client of the web server.
A URL stands for Uniform Resource Locator. It specifies the distinct address for each resource on the Internet. A file's Internet address, or URL, is determined by the following :
Thus, the format of a URL is as follows: type://address/path
For example, http://encycle.msn.com/getinfo/styles.asp
Here, http: — specifies the type of server
encycle.msn.com — is the address of server
getinfo/style.asp — is the path of the file styles.asp.
The characters based naming system by which servers are identified is known as domain name system (DNS). In this system, the internet address of a server is represented by a characters based named followed by a suffix which together is termed as the domain name of the server.
Some commonly used domain name suffixes are as follows:
Domain Id | Purpose |
---|---|
com | for commercial firms |
edu | for educational firms |
gov | for government organizations / bodies |
mil | for Military |
net | for ISPs/networks |
org | for NGOs and other non-profit |
co | for listed companies |
biz | for business |
tv | for television companies and channels |
Web Hosting is a means of hosting web-server application on a computer system through which electronic content on the Internet is readily available to any web-browser client.
The various categories of web hosting are as follows:
HTML stands for Hyper Text Markup Language. It is a markup language, which is used to define the layout and attributes of a World Wide Web (WWW) document, to create links between web pages, to display data on the internet and help in making the web pages look attractive.
XML stands for Extensible Markup Language. It is a meta-language for describing markup languages. It provides facility to define tags and the structural relationships between them. All the semantics of an XML document will either be defined by the applications that process them or by stylesheets.
DHTML refers to web content that changes each time it is viewed. It refers to new HTML extensions that will enable a web page to react to user input without sending requests to the web server. It is typically used to describe the combination of HTML, style sheets and scripts that allows documents to be animated.
Network security refers to making sure that only legal or authorized users and programs gain access to information resources like databases. Also, certain control mechanisms are setup to ensure that properly authenticated users get access only to those resources that they are entitled to use.
Network security is very important because data travels through a network. Protection of data and its secure transmission is only possible if methods are employed to secure the network from various threats like physical/software security holes, inconsistent usage holes, hacking, cracking, etc.
The system designed to prevent unauthorized access to or from a private network is called Firewall.
There are several types of firewall techniques :
Hacking is the unauthorized access of a computer system and networks.
Cracking refers to breaking into secure systems with the purpose of stealing and corrupting data.
Cracking and hacking both refer to the unauthorized access of a computer system. They just have different intentions behind them. Cracking is done with malicious intentions whereas hacking is done for gaining knowledge about computer systems and possibly using this knowledge to find lack in security or for playful pranks.
In India, the cyber laws are enforced through Information Technology Act, 2000 which was notified on 17 October 2000. It's prime purpose was to provide legal recognition to electronic commerce and to facilitate filing of electronic records with the Government, i.e., to provide the legal infrastructure for e-commerce in India.
The Act was later amended in December 2008 through the IT (Amendment) Act, 2008. It provided additional focus on Information Security. It has added several new sections on offences including Cyber Terrorism and Data Protection. The Information Technology Amendment Act, 2008 (IT Act 2008) came into force from October 27, 2009 onwards. Major amendments of IT ACT (2008) included digital signatures, electronic governance, offences and penalties and amendments to other laws.
Intellectual property rights (IPR) are legal rights, which result from intellectual activity in the industrial, scientific, literary and artistic fields. These rights:
We prefer switch over other network devices when we need to establish two-lane communication, facilitating send and receives at the same time. A switch provides full bandwidth to each connection and sends traffic only to appropriate connections, thus preventing traffic overload.
We would opt for a router in a network when we want to connect different networks working on different protocols. A router makes the system more reliable as if a link between two routers fails, the sending router can determine an alternate route to keep traffic moving.
Client-side scripting | Server-side scripting |
---|---|
Script code is downloaded and executed at client. | The script is executed at the server-end and the result is sent to the client-end. |
Response to interaction is more immediate once the program code has been downloaded. | Complex processes are more efficient as the program and associated resources are not downloaded to the browser. |
Services are secure as they do not have access to files and databases. | Have access to files and data bases but have security considerations when sending sensitive information. |
Browser dependent | Does not depend on browsers. |
Affected by the processing speed of user's computer. | Affected by the processing speed of the host server. |
Viruses can cause damage in many ways. They can:
We can protect our computers from viruses by following some simple guidelines:
HTTP | HTTPS |
---|---|
The full form of HTTP is Hypertext Transfer Protocol. | The full form of HTTPS is Hypertext Transfer Protocol Secure. |
HTTP is the set of rules for transferring hypertext on world wide web (WWW). | HTTPS is a secure version of the HTTP protocol that uses the SSL/TLS protocol for encryption and authentication. |
HTTP sends data in plain text. | HTTPS sends the data in encrypted form to make the transmission secure. |
URLs using HTTP start with "http://". | URLs using HTTPS start with "https://". |
IMAP (Internet Message Access Protocol) is a standard protocol for accessing e-mail from local server. IMAP is a client/server protocol in which e-mail is received and held for the user by internet server. IMAP holds the email until the user actually deletes it. As this requires only a small data transfer this works well even over a slow connection such as a modem. Only if the user requests to read a specific email message, then it will be downloaded from the server.
The POP3 (Post Office Protocol 3) protocol provides a simple, standardized way for users to access mailboxes and download messages to their computers. POP3 holds the email until the user actually receives/downloads the email. When using the POP3 protocol, all the eMail messages get downloaded from the mail server to the user's local computer. The user can choose to leave copies of his/her eMails on the server as well. The advantage is that once messages are downloaded, the user can cut the internet connection and read his/her eMail at own leisure without incurring further communication costs. On the other hand he/she might have transferred a lot of message (including spam and viruses), which may prove dangerous for data on PC.
A protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
HTTP (Hyper Text Transfer Protocol) is used to search information from Internet using an Internet browser.
A protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.
File Transfer Protocol (FTP) is used to copy a file from/to a remotely located server.
Webpage | Website |
---|---|
The documents residing on websites are called webpages. | A location on a web server is called a website. |
Each web page is identified by a unique web address called Uniform Resource Locator (URL) within a domain. | A website has all its web pages accessible via the same domain name. |
It contains specific content such as text, images, videos etc. | It consists of multiple webpages interconnected through links. |
Web browser | Web server |
---|---|
A web browser is a world wide web client that navigates through the world wide web and displays web pages. | A web server is a world wide web server that responds to the requests made by web browsers. |
For example : Internet Explorer, Google chrome | For example : Apache Tomcat, Webserver IIS |
Web Hosting is a means of hosting web-server application on a computer system through which electronic content on the Internet is readily available to any web-browser client.
The significance of web hosting is that web hosts allow their customers to place web documents, such as HTML pages, graphics, and other multimedia files, onto a special type of computer called a web server. This server maintains constant, high-speed connections to the backbone of the Internet.
To run a Telnet session, we first have to run the telnet client and then connect to the desired telnet site. All this is illustrated in following steps :
The functioning of Telnet involves initiating a Telnet session by running a Telnet client and connecting to a remote system. This process typically includes steps such as connecting to the desired Telnet site, navigating through a connect dialog, accessing the default menu of the Telnet site, performing actions like specifying search terms, viewing search results, and accessing further details if required. Finally, the session is terminated by disconnecting from the remote system.
False
Reason — A gateway is not like a modem because it connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely different structures. On the other hand, a modem modulates digital data from the sender computer into analog form to travel over the telephone lines to the target computer and demodulates received analog data into digital form for the target computer.
False
Reason — A repeater is a network device that amplifies and restores signals for long-distance transmission. Whereas amplifier amplifies all incoming signals over the network. It amplifies both the signal and any concurrent noise. Therefore, an amplifier and a repeater have distinct functions.
True
Reason — A hub is networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together. Hub broadcasts the message to all nodes in the network, only the target node takes the message while others ignore it.
True
Reason — A switch is called as an "intelligent hub" because it can direct data specifically to the intended device connected to it, unlike a hub that just sends data to all connected devices. This makes a switch more efficient for managing network traffic.
False
Reason — A repeater is a network device that amplifies and restores signals for long-distance transmission. Whereas a router is a network device that forwards data from one network to another. A router works like a bridge but can handle different protocols. Hence, repeater and router work differently.
False
Reason — A bridge is a device that connects two networks together and can handle networks that follow the same protocols. On the other hand, a router is a network device that forwards data from one network to another. It functions similarly to a bridge but can handle different protocols. A router differs from a bridge in that the former uses logical addresses, while the latter uses physical addresses.
True
Reason — TCP/IP is responsible for providing reliable data transmission between networked computers by splitting messages into smaller packets if required. It handles addressing, mapping, and acknowledgment of data packets to ensure successful delivery across the network. Additionally, it keeps track of what is sent and retransmits anything that did not get through. Therefore, data packets can arrive at different times at the final location.
False
Reason — The HTTP (Hypertext Transfer Protocol) is the set of rules for transferring hypertext on world wide web (WWW). Whereas HTTPS (Hypertext Transfer Protocol Secure) is a secure version of the HTTP protocol that uses the SSL/TLS protocol for encryption and authentication.
True
Reason — A switch is called as an "intelligent hub" because it can direct data specifically to the intended device connected to it, unlike a hub that just sends data to all connected devices. This makes a switch more efficient for managing network traffic.
True
Reason — Both hackers and crackers do the same thing, i.e., hack a system but with different intentions. Hackers are technically sound people who hack devices and systems with good intentions, such as to find the security lapses of a system, in order to rectify it or for obtaining more knowledge out of it. But crackers are technically sound people with malicious intentions who hack a system by breaking into it and violating it for some bad motives.
True
Reason — True. Both a computer virus and antivirus software are programs. A computer virus is a malicious program that requires a host and is designed to make a system sick, just like a real virus. Whereas an antivirus is a specially designed program designed to detect and remove viruses and other kinds of malicious software from computer or laptop and other devices.