 Introduction
 What is a Network
 Need for networking
 Elementary Terminology of Networks
 Domain Name Resolution
 Network Topologies
 Type of Networks
 Transmission Media
 Network Devices
 Network Security
What is Computer Networking …………?
A computer network is a
set
of
computers
connected with each
other in order to share
resources & information.
Resources means – the devices which are connected with the computer system like Printer
Scanner etc.
Need for Networking …………?
Requirement of a network have two major era.
(1) Networks Goals
(A) Resource Sharing
(B) Reliability
(C) Cost Factor
(D) Communication Media
(1) Application of Network
(A) Sharing
(B) Access remote database
(C) Communication facilities
Elementary Terminology of Networks
Nodes (Workstation)- The term node refers to the
computer that are connected to the network.
Server – A Compute that facilitates the sharing of data,
software and hardware resource on the network , A
server may be two type (1) non-dedicated server (2)
dedicated server.
Network Interface Unit [NIU]/ Network Interface Card
[NIC]/Terminal Access Point [TAP] - NIU is an interface
(network devices/network card) that helps establish
communication between the server and nodes
(workstation).
Elementary Terminology of Networks …………………….
MAC Address (Media Access Control) The NIC
manufacture assigns a unique physical address to each NIC ;
this address is called MAC address. A MAC address is 6 byte
address each byte separated by a colon
For example –
10:B5:03 (Manufacture ID): 63:2E:FC (Card No)
IP Address- All network follow some rules for
communication these rules are called as protocols, every
machine (computer system) on a TCP/IP network has a
unique identifying number , called an IP address
For example –
216.27.61.137 IP address in decimal form
To know the IP address for our computer system
We can use ipconfig command
Elementary Terminology of Networks ………………….
Domain Name (or Domain Name System )DNS
Domain Name is a unique name assigned to a
website, A Domain name contains the following
parts :(1) www
(2) Name describing the website
(3) TLD (Top Level Domain)
Example – www.kv1gcfjabalpur.com
Hear com is TLD (Top Level Domain)
Elementary Terminology of Networks ………………….
Domain Name Resolution
It is a way to obtained corresponding IP address from a domain
name.
How it works
When we enter a domain name (website) using any web browser it
issue a command to operating system to provide corresponding IP
address,
Operating System tries to resolve the domain name as per its
configuration(different OS have different configuration ), in general
OS perform the following
(1) Refer to its HOSTS file (a file used by OS to maintain the IP
address of some domain)
(2) If 1st option fails then OS connects to a DNS server on Internet
(DNS server maintain a directory of IP address of all domain
registered
After obtaining IP address OS pass it to the browser that demanded
Network Topologies
Topologies are the pattern of interconnection of
nodes (computers) in a network. A topology is
affects by the following factors :(1)Cost
(2)Flexibility
(3)Reliability
Point to Point link it works upon two function (transmit and receive). The main
characteristic of P-P Network is that – each station receive
exactly from one transmitter and each transmitter transmit
exactly one receiver
Network Topologies ………………The Star Topology
This topology consist of a central
node (server) to which all other
nodes are connected by a single
path.
Advantage –
 Easy to install
 Easy to detect faults
 One device per connection
 Simple access protocol
Dis- Advantage –
 Need long cable
 Not easy to expand
 Central node(server)
dependency
node
Network Topologies ………………The Bus/Linear Topology
This topology consist of a single length of
transmission media (normally coaxial cable)
central node (server) to which all other
nodes are connected by a single path.
Advantage –
 Short cable and simple wiring layout
 Easy to extend, easy to connect new
node
 No central control.
Dis- Advantage –
 Difficult to diagnosis fault
 Need repeater
 Addition of nodes negatively affects the
performance of whole network
Network Topologies ……………… Ring/Circular Topology
In a ring network, every node has
exactly two neighbors for
communication purpose. Data
travels in one direction only.
Advantage –
 Very Short cable required.
 Suitable for optical fibers.
 All station has equal access.
Dis- Advantage –
 Difficult to diagnosis fault
 Node failure causes network
failure
 Complex to extend network.
Network Topologies ……………… TREE Topology
The shape of the network is that of
an inverted TREE, it have
characteristic of liner and star
topologies.
Advantage –
 Point to point wiring for
individual segments
 Supported by several
hardware and software
Dis- Advantage –
 If backbone line fail entire
system goes down
 More difficult to configure and
wire than other topologies
Network Topologies ……………… Graph,Mesh & fully Topology
Graph- In this topology nodes are
connected in arbitary fashion, a
link may or may not connected two
or more nodes.
Mesh - In this topology each node
is connected with more than one
node to provide alternative route.
Fully - In this topology a node is
directly connected with other .
Type of Network
LAN- Local Area Network it is
confined to a localized are (an
building, office …)
MAN (Metropolitan Area Network)
– it is spread over a city
WAN (Wide area Network) it is
group of computers that have
large distance and tied toghter.
Transmission Media
(Connecting cable and connecting media in a network)
Transmission media is a media by which nodes are
connected with each other . A transmission media may
be the following –
1.
2.
3.
4.
5.
6.
Twisted Pair cable
Coaxial Cable
Optical Fibers
Microwave
Radio Wave
Satellite
Twisted Pair Cable
It is common form of
wiring in data
communication.
Advantage – inexpensive,
simple , easy to install and
maintain ,
Disadvantage – not good
for long distance, data
transfer rate is low
Coaxial Cable
It consists of a solid wire core
surrounded by one or more foil
or wire shields each separated
by some kind of plastic
insulator
Advantage – better data rate ,
can easy install
Disadvantage- expensive as
compared to twisted cable, it
may not compatible with
twisted cable
Network Devices
Modem – It is a devices that
allows us to connect and
communicate with other
computer via telephone lines.
It may be two types
(1) Internal
(2) External
Network Devices
Hub – It is a hardware devices
that allows us to connect
several computer together
It may be two types
(1) Active Hub
(2) Passive Hub
Network Devices…………
Switch – It is a devices that is
used to segment network into
different sub-network, called
subnet or LAN segment. A
switch is responsible for filtering
i.e. transforming data in a
specific way.
Network Devices…………
Repeater – It is a devices
that amplifies and restores
signals for long distance
communication
Network Devices…………
Gateway– It is a devices that
connects dissimilar
networks(having different
protocols), it create an
intelligent connection between
a local network and external
network
Network Devices…………
Bridge – It is a devices that
connects two local network
having same protocols, its
works with MAC address
Network Devices…………
Router – It is a devices that
connects multiple network
irrespective of their protocols.
Router can handle different
protocols
Network Security
Network security is the ability of a system to protect
information and system resources with respect to
confidentiality and integrity
“Freedom from risk or danger.”
Network security is an important issue as
so many people business man are
dependent on computer for their day to
day work
Intrusion Problems/Access Attacks
When an authorized user attempts to gain access to
protected sensitive information . It is known as Access
attacks or (Intrusion Problem). This type of attacks is an
attack against confidentiality of information
Snooping
It refers to open and looking through files in unauthorized
manner. It may involve many types of things such as –
gaining access of data in unauthorized way, observing e
mails, monitoring activity
The various possible sources of attack to a system
are as follows:
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Virus
Worms
Trojans
Phishing
Spyware
PC Intrusion
DoS (Denial of Service)
Sweeper attack
Password guessing
Spamming
Adware
Computer Virus : it is a self propagating computer
program designed to alter or destroy a computer
system resource. they use software (executable code
for grow)
Worm – worms are very much same to virus. A
worm does not need another executable code to
distributed , they reproduce themselves across
network.
Trojans – it is a malicious(ख़राब/ दष्ु ट) computer
program that pretends (मान लेना)to do one things
but actually does something different.
Phishing : Phishing is the attempt to
acquire sensitive information such as usernames,
passwords, and credit card details (and sometimes,
indirectly, money),
Spyware – this is a technology to gathering
information about a person or organization with out
their knowledge
DoS(Denial of Service) – A DoS attack can be define
as an attack to denial of the service
Network Security Measure : it is combination of
Identification , authentication and authorization
that can control access to computer system
Network Security Measure
• Authorization – providing user ID and
password
• Authentication – when his / her user ID
and password is considered as valid
than he/she may be authentic user.
• Firewall- a system design to prevent
unauthorized access to or from a
private network.
• Implement proper security policy for
your organization.
• Use proper file access permission when
sharing files on the internet
• Disconnect from the internet when
away.
• When we download/upload any file –
FTP (File transfer protocols)
• When we send a email- SMTP(Simple
Mail Transfer protocol)
• When we received a email – POP (Post
office Protocol)
• When we read textual information
(HTTP Hyper text transfer protocol)