1. What do you mean by computer network? Write its advantages, types and use in detail.
Ans: Computer Network
Computer network is a group of computers or devices are connected together by communication link. It means an interconnected collection of autonomous computers. Computers are in network only when they are able to exchange information. A large number of users belonging to same are or same organization but spread over at different places can communicate and share useful files, software and information at right times via network computers.
Advantages of Computer Network
The advantages of computer network are explained as follows:
- File sharing and flexible access: Network file sharing between computers fives more flexibility than using removable drives. Photo, files, documents can be shared. All the users may /can access files from computers throughout the network. Multiple users can also collaborate on the same project through
- Resource sharing: All computers in
networkcan share resources such as printer, fax machine, modems andscanners.
- Software cost and management: Software is available for networks at
a substantial savingsin comparison to buying individually licensed copied for all computers. Management is also easier as installing and upgrading have to be done once on the file server ofon individual workstations.
- Communication: People on the network can communicate with each other via electronic mail over the network even without connection with
internet. Internetcan be shared by all the users in the network.
Type of Computer Network
The types of computer network are explained briefly:
ii. Metropolitan Area Network (MAN): In MAN, the communication infrastructures are developed in and around large cities. MAN is larger than LAN and smaller than WAN. Example: microwave links in banks, cooperated offices with in different cities. It has less error rate than WAN and higher data rate than WAN.
iii. Wide Area Network (MAN): A network that connects local area networks over a potentially large geographic distance. A WAN consists of number of interconnected switching nodes. These nodes are not concerned with the content of the data rather their purpose is to provide switching facilities. Communication channels between the networks are usually furnished by a third party. (Like telephone company, a public data network, satellite carrier etc. Channel is relatively low capacity (kbps). Channel has bit error rate of 1 in 100000 bits transmitted).
Uses of Computer Network
There are various uses of network and used in different fields like education, medical, business, communication, research etc. Some of the basic uses of network are:
i. Resource Sharing: Network is used mostly for resources sharing. Limited resources like printer, modem, camera etc. can be shared by multiple users in the network. Internet connection sharing is possible.
ii. Remote login and file sharing: By networking, user can remotely login and access different computer and file in them. Users at different locations can access different locations computers. Multiple users can collaborate on the same project through the network.
iii. Communication and entertainment: Network is used for different type of communication like email, text, video or voice chat. Networks are used for different gaming and entertainment purpose.
iv. Management of Organizational Activities: Networking is done for different management and organizational activities. Management information system is also based on networking. Employee performance, attendance, feedback and monitoring can be done using networking based application software.
2. Explain the function of the following commands with syntax:
(i) COPY CON (ii) VER (iii) DEL (iv) SCANDISK (v) EDIT (vi) MD (vii) REN
Ans: (i) COPY CON:
It is an internal command. The COPY CON command along with file name is used to create a new file in MS-DOS.
Syntax: COPY CON filename [ext.]
C:\>COPY CONT Test
After this type the text and save by pressing F6 or Ctrl + Z.
It is internal command. Display the MS-DOS version in use.
DEL command is used to delete a file or group of files.
Wildcard (? and *) may be used in the file name is the deletion command.
This command can be used to delete files of another drive.
Syntax: DEL [drive:] [path] filename [ext]
It deletes the file Test of C: drive.
It repairs the disks. It checks the surface of disk.
It is on external common.
Syntax: Scandisk [drive:][/All] [/CHECKONLY][/AUTOFIX]
To check and repair the disk at current drive.
It is used to compile, edit, save, copy and print straight forward ad simple text.
Syntax: EDIT [drive:][path] filename
Create a directory
Syntax: MD [drive:] path.
e.g. C:\>MD Test
Creates text directory in C drive.
REN common allows to change the name of file or sub directory.
Syntax: REN[drive:][path] <old filename> <new filename>
C:\>REN PEN PEN1
(old file) (new file)
Changes the old PEN to PEN1 but content remains same.
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3. Explain the following command of DOS with syntax and suitable example. MKDIR, EDIT, SYS, DIR/S/P/W, CHKDSK.
Ans: (i) MKDIR: 2003 fall 2(b)(i)
(ii) EDIT: 2003 fall 2 b (v)
(iii) SYS: Sys is used to copy the system files from one drive to another allowing that drive to be bootable.
SYS [drive 1:][path] drive 2:
e.g.: C:\sys a:
This would copy system files to a: making that disk bootable.
(iv) DIR/S/P/W: 2003 fall 2 (b) (ii)
(v) CHKDSK: Chkdsk is a utility that check the computer’s hard disk drives’ status for any cross – linked or any additional error with the hard disk drive.
CHKDSK [drive :][path][/F][/V]
[drive][path]: Specifies the drive and directory to check.
File name: Specifies the file(s) to check for fragmentation.
/F: Fixes errors on disk.
/V: Display the full path and name of every file on the disk.
4. Explain the following command of DOS with syntax and suitable example.
Ans: (i) ATTRIB:
Attribute common refers to the current attributes of file/files. Attributes are Hidden (+H), Read and Write (-R), Read Only (+R), Archive Boot Not Set (-A), Archive Boot Set (+A) and System Status (+-S).
Syntax: ATTRIB [-R/+R][-A/+A][-S/+S][-H/+H][drive:][path][filename]
e.g. C:\>ATTRIB + R Text. doc
This will set the file attribute to read only status.
(ii) DISKCOPY: The DISKCOPY command copies the content of a diskette to a new diskette without any alteration.
Syntax: DISKCOPY [source:][target:][/L][N]
e.g. C:\>diskcopy A: A:
It performs discopying in the same drive.
(iii) COPY CON:
Please see the answer of 2005 spring 2(b)(i)
(iv) RD: RD command removes as empty directory from parent directory.
Syntax: RD [drive:] path
e.g. C:\>RD POM
It remove directory POM if it is empty
(v) DELTREE: Deltree command deletes a directory and all of its files and sub-directories, including hidden file, system files and read – only files.
Syntax: DELETEEE [/Y][drive:][path]
e.g. C:\> DELTREE A:\POM
Deletes all files inside directory and directory.
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5. Discuss about the different types of cable communication media used in networking with their merits and demerits.
Ans: The different types of cable communication media in networking are:
(i) Twisted pair: Twisted pair wire is placed inside a thin metallic shielding, similar to aluminum foil, and is then enclosed in an outer plastic casing. Twisted pair cable consists of pair of insulated wires twisted together. It is a cable type used in telecommunication for very long time. Cable twisting helps to reduce noise pickup from outside sources and crosstalk on multi-pair cables.
Twisted pair cable is good for transferring balanced differential signals. The practice of transmitting signals differentially dates back to the early days of telegraph and radio. The advantages of improved signal-to-noise ratio, crosstalk, and ground bounce that balanced signal transmission brings are particularly valuable in wide bandwidth and high fidelity systems. By transmitting signals along with a 180 degree out-of-phase complement, emissions and ground currents are theoretically canceled.
Merits of twisted pair cable are:
- It is a thin, flexible cable that is easy to string between walls.
- More lines can be run through the same wiring ducts.
- UTP costs less per meter/ foot than any other types of LAN cable.
- Susceptible to interference.
- Can cover only limited distance.
(ii) Coaxial Cable:
Coaxial cable consists of hollow outer cylindrical conductor that surrounds a signal inner wire made of two conducting elements. One of these elements, located in the center of the cable, is a copper conductor. Surrounding the copper conductor is a layer of flexible insulation. Over this insulating material is a woven copper braid or metallic foil that acts both as the second wire in the circuit and as a shield for the inner conductor. This second layer, or shield, can help reduce the amount of outside interference. Covering this shield is the cable jacket. Coaxial cable supports 10 to 100 Mbps and is relatively inexpensive, although it is more costly than UTP on a per-unit length.
- Less susceptible to EMI interference than other types of copper media.
- Higher data rate.
- Long distance communication.
- Difficult to work with.
- Relatively expensive.
- Damage to cable can bring down entire network.
(iii) Optical Fiber:
An optical fiber is a thin, flexible, transparent fiber that acts as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distance and at higher bandwidths (data rates) than other forms of communication. Fiber are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference.
- Small in size.
- Higher data rate.
- Longer distance transmission.
- Immune to electromagnetic interference.
- Higher security
- Wiring and joining is complex than other media.
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