1. The document discusses various computer network types including personal area networks (PAN), local area networks (LAN), metropolitan area networks (MAN), wide area networks (WAN) and internetworks. 2. It also covers common LAN technologies like Ethernet, Fast Ethernet, Gigabit Ethernet and virtual LANs. Different network topologies such as star, bus, ring and mesh are described. 3. The number systems used in computers like binary, octal and hexadecimal are explained along with examples of how to convert between number systems.

1. Assignment
Of
Information technology
For
Management

2. SUBMITTEDTO:
Mr.sunildalhotra
SUBMITTEDBY:Navneetkaur

3. MBA-1
What is a computer network?
The telecommunication network that permits the computers to exchange the data is known as a
computer network or a data network. Furthermore, in computer networks, the networked
computing devices simply exchange the data with one another with the help of a data link.
Connections happen to be established between the nodes either by a wireless media or by a cable
media. Internet can be termed to be the best example for a computer network.
Generally, networks are distinguished based on their geographical span. A network can be as
small as distance between your mobile phone and its Bluetooth headphone and as large as the
internet itself, covering the whole geographical world,
Personal Area Network
A Personal Area Network (PAN) is smallest network which is very personal to a user. This may
include Bluetooth enabled devices or infra-red enabled devices. PAN has connectivity range up
to 10 meters. PAN may include wireless computer keyboard and mouse, Bluetooth enabled
headphones, wireless printers and TV remotes.

4. For example, Piconet is Bluetooth-enabled Personal Area Network which may contain up to 8
devices connected together in a master-slave fashion.
Local Area Network
A computer network spanned inside a building and operated under single administrative system
is generally termed as Local Area Network (LAN). Usually,LAN covers an organization’ offices,
schools, colleges or universities. Number of systems connected in LAN may vary from as least
as two to as much as 16 million.
LAN provides a useful way of sharing the resources between end users.The resources such as
printers, file servers, scanners, and internet are easily sharable among computers.
LANs are composed of inexpensive networking and routing equipment. It may contains local
servers serving file storage and other locally shared applications. It mostly operates on private IP
addresses and does not involve heavy routing. LAN works under its own local domain and
controlled centrally.
LAN uses either Ethernet or Token-ring technology. Ethernet is most widely employed LAN
technology and uses Star topology, while Token-ring is rarely seen.
LAN can be wired,wireless, or in both forms at once

5. .
Metropolitan Area Network
The Metropolitan Area Network (MAN) generally expands throughout a city such as cable TV
network. It can be in the form of Ethernet,Token-ring, ATM, or Fiber Distributed Data Interface
(FDDI).
Metro Ethernet is a service which is provided by ISPs. This service enables its users to expand
their Local Area Networks. For example, MAN can help an organization to connect all of its
offices in a city.
Backbone of MAN is high-capacity and high-speed fiber optics. MAN works in between Local
Area Network and Wide Area Network. MAN provides uplink for LANs to WANs or internet
.

6. Wide Area Network
As the name suggests,the Wide Area Network (WAN) covers a wide area which may span across
provinces and even a whole country. Generally, telecommunication networks are Wide Area
Network. These networks provide connectivity to MANs and LANs. Since they are equipped
with very high speed backbone, WANs use very expensive network equipment.
WAN may use advanced technologies such as Asynchronous Transfer Mode (ATM), Frame
Relay, and Synchronous Optical Network (SONET). WAN may be managed by multiple
administration.
Internetwork
A network of networks is called an internetwork, or simply the internet. It is the largest network
in existence on this planet.The internet hugely connects all WANs and it can have connection to
LANs and Home networks. Internet uses TCP/IP protocol suite and uses IP as its addressing
protocol. Present day, Internet is widely implemented using IPv4. Because of shortage of address
spaces, it is gradually migrating from IPv4 to IPv6.
Internet enables its users to share and access enormous amount of information worldwide. It uses
WWW, FTP, email services, audio and video streaming etc. At huge level, internet works on
Client-Server model.
Internet uses very high speed backbone of fiber optics. To inter-connect various continents,
fibers are laid under sea known to us as submarine communication cable.
Internet is widely deployed on World Wide Web services using HTML linked pages and is
accessible by client software known as Web Browsers. When a user requests a page using some

7. web browser located on some Web Server anywhere in the world, the Web Server responds with
the proper HTML page. The communication delay is very low.
Internet is serving many proposes and is involved in many aspects of life. Some of them are:
 Web sites
 E-mail
 Instant Messaging
 Blogging
 Social Media
 Marketing
 Networking
 Resource Sharing
 Audio and Video Streaming
 Ethernet
 Ethernet is a widely deployed LAN technology.This technology was invented by Bob
Metcalfe and D.R. Boggs in the year 1970. It was standardized in IEEE 802.3 in 1980.
 Ethernet shares media. Network which uses shared media has high probability of data
collision. Ethernet uses Carrier Sense Multi Access/Collision Detection (CSMA/CD)
technology to detect collisions. On the occurrence of collision in Ethernet, all its hosts
roll back, wait for some random amount of time, and then re-transmit the data.
 Ethernet connector is,network interface card equipped with 48-bits MAC address. This
helps other Ethernet devices to identify and communicate with remote devices in
Ethernet.
 Traditional Ethernet uses 10BASE-T specifications.The number 10 depicts 10MBPS
speed, BASE stands for baseband, and T stands for Thick Ethernet. 10BASE-T Ethernet
provides transmission speed up to 10MBPS and uses coaxial cable or Cat-5 twisted pair
cable with RJ-45 connector. Ethernet follows star topology with segment length up to 100
meters. All devices are connected to a hub/switch in a star fashion.
 Fast-Ethernet
 To encompass need of fast emerging software and hardware technologies, Ethernet
extends itself as Fast-Ethernet. It can run on UTP, Optical Fiber, and wirelessly too. It
can provide speed up to 100 MBPS. This standard is named as 100BASE-T in IEEE
803.2 using Cat-5 twisted pair cable. It uses CSMA/CD technique for wired media
sharing among the Ethernet hosts and CSMA/CA (CA stands for Collision Avoidance)
technique for wireless Ethernet LAN.
 Fast Ethernet on fiber is defined under 100BASE-FX standard which provides speed up
to 100 MBPS on fiber. Ethernet over fiber can be extended up to 100 meters in half-
duplex mode and can reach maximum of 2000 meters in full-duplex over multimode
fibers.
 Giga-Ethernet
 After being introduced in 1995, Fast-Ethernet could enjoy its high speed status only for 3
years till Giga-Ethernet introduced. Giga-Ethernet provides speed up to 1000
mbits/seconds. IEEE802.3ab standardize Giga-Ethernet over UTP using Cat-5, Cat-5e
and Cat-6 cables. IEEE802.3ah defines Giga-Ethernet over Fiber.

8.  Virtual LAN
 LAN uses Ethernet which in turn works on shared media. Shared media in Ethernet
create one single Broadcast domain and one single Collision domain. Introduction of
switches to Ethernet has removed single collision domain issue and each device
connected to switch works in its separate collision domain. But even Switches cannot
divide a network into separate Broadcast domains.
 Virtual LAN is a solution to divide a single Broadcast domain into multiple Broadcast
domains. Host in one VLAN cannot speak to a host in another. By default, all hosts are
placed into the same VLAN.

 In this diagram, different VLANs are depicted in different color codes. Hosts in one
VLAN, even if connected on the same Switch cannot see or speak to other hosts in
different VLANs. VLAN is Layer-2 technology which works closely on Ethernet. To
route packets between two different VLANs a Layer-3 device such as Router is required.
A Network Topology is the arrangement with which computer systems or network devices are
connected to each other. Topologies may define both physical and logical aspect of the network.
Both logical and physical topologies could be same or different in a same network.
Point-to-Point
Point-to-point networks contains exactly two hosts such as computer, switches or routers, servers
connected back to back using a single piece of cable. Often, the receiving end of one host is
connected to sending end of the other and vice-versa.
If the hosts are connected point-to-point logically, then may have multiple intermediate devices.
But the end hosts are unaware of underlying network and see each other as if they are connected
directly.
Bus Topology
In case of Bus topology, all devices share single communication line or cable.Bus topology may
have problem while multiple hosts sending data at the same time. Therefore, Bus topology either
uses CSMA/CD technology or recognizes one host as Bus Master to solve the issue. It is one of
the simple forms of networking where a failure of a device does not affect the other devices. But
failure of the shared communication line can make all other devices stop functioning.

9. Both ends of the shared channel have line terminator. The data is sent in only one direction and
as soon as it reaches the extreme end, the terminator removes the data from the line.
Star Topology
All hosts in Star topology are connected to a central device, known as hub device, using a point-
to-point connection. That is, there exists a point to point connection between hosts and hub. The
hub device can be any of the following:
 Layer-1 device such as hub or repeater
 Layer-2 device such as switch or bridge
 Layer-3 device such as router or gateway
As in Bus topology, hub acts as single point of failure. If hub fails, connectivity of all hosts to all
other hosts fails. Every communication between hosts, takes place through only the hub.Star
topology is not expensive as to connect one more host, only one cable is required and
configuration is simple
.

10. Ring Topology
In ring topology, each host machine connects to exactly two other machines, creating a circular
network structure. When one host tries to communicate or send message to a host which is not
adjacent to it, the data travels through all intermediate hosts. To connect one more host in the
existing structure, the administrator may need only one more extra cable.
Failure of any host results in failure of the whole ring.Thus, every connection in the ring is a
point of failure. There are methods which employ one more backup ring.
Mesh Topology
In this type of topology, a host is connected to one or multiple hosts.This topology has hosts in
point-to-point connection with every other host or may also have hosts which are in point-to-
point connection to few hosts only.
Hosts in Mesh topology also work as relay for other hosts which do not have direct point-to-
point links. Mesh technology comes into two types:
 Full Mesh: All hosts have a point-to-point connection to every other host in the network.
Thus for every new host n(n-1)/2 connections are required. It provides the most reliable
network structure among all network topologies.
 Partially Mesh: Not all hosts have point-to-point connection to every other host. Hosts
connect to each other in some arbitrarily fashion. This topology exists where we need to
provide reliability to some hosts out of all.

11. Tree Topology
Also known as Hierarchical Topology, this is the most common form of network topology in use
presently.This topology imitates as extended Star topology and inherits properties of bus
topology.
This topology divides the network in to multiple levels/layers of network. Mainly in LANs, a
network is bifurcated into three types of network devices. The lowermost is access-layer where
computers are attached. The middle layer is known as distribution layer, which works as
mediator between upper layer and lower layer. The highest layer is known as core layer, and is
central point of the network, i.e. root of the tree from which all nodes fork.
All neighboring hosts have point-to-point connection between them.Similar to the Bus topology,
if the root goes down, then the entire network suffers even.though it is not the single point of
failure. Every connection serves as point of failure, failing of which divides the network into
unreachable segment.

12. Daisy Chain
This topology connects all the hosts in a linear fashion. Similar to Ring topology, all hosts are
connected to two hosts only, except the end hosts.Means, if the end hosts in daisy chain are
connected then it represents Ring topology.
Each link in daisy chain topology represents single point of failure. Every link failure splits the
network into two segments.Every intermediate host works as relay for its immediate hosts.
Hybrid Topology
A network structure whose design contains more than one topology is said to be hybrid topology.
Hybrid topology inherits merits and demerits of all the incorporating topologies.
The above picture represents an arbitrarily hybrid topology. The combining topologies may
contain attributes of Star, Ring, Bus, and Daisy-chain topologies. Most WANs are connected by
means of Dual-Ring topology and networks connected to them are mostly Star topology
networks. Internet is the best example of largest Hybrid topology

13. What are the number systems?
When we type some letters or words, the computer translates them in numbers as computers
can understand only numbers. A computer can understand positional number system where there
are only a few symbols called digits and these symbols represent different values depending on
the position they occupy in the number.
A value of each digit in a number can be determined using
 The digit
 The position of the digit in the number
 The base of the number system (where base is defined as the total number of digits
available in the number system).
Decimal Number System
The number system that we use in our day-to-day life is the decimal number system. Decimal
number system has base 10 as it uses 10 digits from 0 to 9. In decimal number system, the
successive positions to the left of the decimal point represent units, tens, hundreds, thousands
and so on.
Each position represents a specific power of the base (10). For example, the decimal number
1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the hundreds position,
and 1 in the thousands position, and its value can be written as
(1x1000)+ (2x100)+ (3x10)+ (4xl)
(1x103)+ (2x102)+ (3x101)+ (4xl00)

14. 1000 + 200 + 30 + 4
1234
As a computer programmer or an IT professional, you should understand the following number
systems which are frequently used in computers.
S.N. Number System and Description
1
Binary Number System
Base 2. Digits used : 0, 1
2
Octal Number System
Base 8. Digits used : 0 to 7
3
Hexa Decimal Number System
Base 16. Digits used : 0 to 9, Letters used : A- F
Binary Number System
Characteristics of binary number system are as follows:
 Uses two digits, 0 and 1.
 Also called base 2 number system
 Each position in a binary number represents a 0 power of the base (2). Example 20
 Last position in a binary number represents a x power of the base (2). Example 2x where
x represents the last position - 1.
Example
Binary Number : 101012
Calculating Decimal Equivalent:
Step Binary Number Decimal Number
Step 1 101012 ((1 x 24
) + (0 x 23
) + (1 x 22
) + (0 x 21
) + (1 x 20
))10
Step 2 101012 (16 + 0 + 4 + 0 + 1)10
Step 3 101012 2110
Note : 101012 is normally written as 10101.

15. Octal Number System
Characteristics of octal number system are as follows:
 Uses eight digits, 0,1,2,3,4,5,6,7.
 Also called base 8 number system
 Each position in an octal number represents a 0 power of the base (8). Example 80
 Last position in an octal number represents a x power of the base (8). Example 8x where x
represents the last position - 1.
Example
Octal Number : 125708
Calculating Decimal Equivalent:
Step Octal Number Decimal Number
Step 1 125708 ((1 x 84
) + (2 x 83
) + (5 x 82
) + (7 x 81
) + (0 x 80
))10
Step 2 125708 (4096 + 1024 + 320 + 56 + 0)10
Step 3 125708 549610
Note : 125708 is normally written as 12570.
Hexadecimal Number System
Characteristics of hexadecimal number system are as follows:
 Uses 10 digits and 6 letters, 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.
 Letters represents numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F =
15.
 Also called base 16 number system
 Each position in a hexadecimal number represents a 0 power of the base (16). Example
160
 Last position in a hexadecimal number represents a x power of the base (16). Example
16x where x represents the last position - 1.
Example
Hexadecimal Number : 19FDE16
Calculating Decimal Equivalent:

16. Step Binary Number Decimal Number
Step 1 19FDE16 ((1 x 164
) + (9 x 163
) + (F x 162
) + (D x 161
) + (E x 160
))10
Step 2 19FDE16 ((1 x 164
) + (9 x 163
) + (15 x 162
) + (13 x 161
) + (14 x 160
))10
Step 3 19FDE16 (65536+ 36864 + 3840 + 208 + 14)10
Step 4 19FDE16 10646210
Note : 19FDE16 is normally written as 19FDE.
What is the diffence between system software and application
software?
Application software is computer software designed to help the user to perform specific tasks.
System software is computer software designed to operate the computer hardware and to
provide a platform for running application software. System Software Create his own
environment to run itself and run other application
As you already know, all computers require software in order to operate and perform basic tasks.
For instance, software is needed to translate your commands into a form the computer can
understand, to open and close other software programs, to manage your stored files, and to locate
and set up new hardware as it is added to a computer. The type of software used to perform these
tasks is system software—the focus of this chapter. System software runs in the background at
all times, launching other software when needed and making it possible for you to use your
computer.
Computers run two types of software: system software and application software.
➤ System software consists of the operating system and utility programs that control a
computer system and allow you to use your computer. These programs enable the computer to
boot, to launch application programs, and to facilitate important jobs, such as transferring files
from one storage medium to another, configuring your computer to work with the hardware
connected to it, managing files on your hard drive, and protecting your computer system from
unauthorized use.
➤ Application software includes all the programs that allow you to perform specific tasks on
your computer, such as writing a letter, preparing an invoice, viewing a Web page, listening to a

17. music file, checking the inventory of a particular product, playing a game, preparing financial
statements, designing a home, and so forth.
In practice, the difference between system and application software is not always
straightforward. Some programs, such as those used to burn DVDs, were originally viewed as
utility programs. Today, these programs typically contain a variety of additional features, such as
the ability to organize and play music and other media files, transfer videos and digital photos to
a computer, edit videos and photos, create DVD movies, copy CDs and DVDs, and create slide
shows. Consequently, these programs now fit the definition of application programs more
closely. On the other hand, system software today typically contains several application software
components. For example, the Microsoft Windows operating system includes a variety of
application programs including a Web browser, a calculator, a calendar program, a painting
program, a media player, a movie making program, an instant messaging program, and a text
editing program. A program’s classification as system or application software usually depends
on the principal function of the program, and the distinction between the two categories is not
always clear cut.
7 layers of TCP/IP protocol
The Open System Interconnection (OSI) model defines a networking framework to
implement protocols in seven layers. Use this handy guide to compare the different layers
of the OSI model and understand how they interact with each other.
The Open System Interconnection (OSI) model defines a networking framework to implement
protocols in seven layers. In the OSI model, control is passed from one layer to the next, starting
at the application layer in one station, and proceeding to the bottom layer, over the channel to the
next station and back up the hierarchy.

18. The OSI Model is Not Tangible
There is really nothing to the OSI model. In fact, it's not even tangible. The OSI model doesn't
perform any functions in the networking process. It is a conceptual framework so we can better
understand complex interactions that are happening.
The OSI Model Layers
The OSI model takes the task of internetworking and divides that up into what is referred to as a
vertical stack that consists of the following 7 layers:
Physical (Layer 1)
OSI Model, Layer 1 conveys the bit stream - electrical impulse, light or radio signal — through
the network at the electrical and mechanical level. It provides the hardware means of sending and
receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet,
RS232, and ATM are protocols with physical layer components.
Layer 1 Physical examples include Ethernet, FDDI, B8ZS, V.35, V.24, RJ45.
Data Link (Layer 2)

19. At OSI Model, Layer 2, data packets are encoded and decoded into bits. It furnishes transmission
protocol knowledge and management and handles errors in the physical layer, flow control and
frame synchronization. The data link layer is divided into two sub layers: The Media Access
Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sub layer controls
how a computer on the network gains access to the data and permission to transmit it. The LLC
layer controls frame synchronization, flow control and error checking.
Layer 2 Data Link examples include PPP, FDDI, ATM, IEEE 802.5/ 802.2, IEEE 802.3/802.2,
HDLC, Frame Relay.
Network (Layer 3)
Layer 3 provides switching and routing technologies, creating logical paths, known as virtual
circuits, for transmitting data from node to node. Routing and forwarding are functions of this
layer, as well as addressing, internetworking, error handling, congestion control and packet
sequencing.
Layer 3 Network examples include AppleTalk DDP, IP, IPX.
Transport (Layer 4)
OSI Model, Layer 4, provides transparent transfer of data between end systems, or hosts, and is
responsible for end-to-end error recovery and flow control. It ensures complete data transfer.
Layer 4 Transport examples include SPX, TCP, UDP.
Session (Layer 5)
This layer establishes, manages and terminates connections between applications. The session
layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the
applications at each end. It deals with session and connection coordination.
Layer 5 Session examples include NFS, NetBios names, RPC, SQL.
Presentation (Layer 6)
This layer provides independence from differences in data representation (e.g., encryption) by
translating from application to network format, and vice versa. The presentation layer works to
transform data into the form that the application layer can accept. This layer formats and
encrypts data to be sent across a network, providing freedom from compatibility problems. It is
sometimes called the syntax layer.
Layer 6 Presentation examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG,
MPEG, MIDI.

20. Application (Layer 7)
OSI Model, Layer 7, supports application and end-user processes. Communication partners are
identified, quality of service is identified, user authentication and privacy are considered, and any
constraints on data syntax are identified. Everything at this layer is application-specific. This
layer provides application services for file transfers, e-mail, and other network software services.
Telnet and FTP are applications that exist entirely in the application level. Tiered application
architectures are part of this layer. Layer 7 Application examples include WWW browsers,
NFS, SNMP, Telnet, HTTP, FTP
Thankyou…..