• Computer Network: A group of computers & other peripheral devices that are all linked togethers for the purpose of sharing data and hardware resources.
• Node: Each computer in a network is called a Node.

Computer Network as a Data Communication System

Components of Data Communication

1. Message : Message is the information to be communicated by the sender to the receiver.
2. Sender : The sender is any device that is capable of sending the data (message).
3. Receiver : The receiver is a device that the sender wants to communicate the data (message).
4. Transmission Medium : It is the path by which the message travels from sender to receiver. It can be wired or wireless and many subtypes in both.
5. Protocol : A Protocol is defined as a set of rules that governs data communications. A protocol defines what is to be communicated, how it is to be communicated and when it is to be communicated.

Networking Media

1. Wired : Ethernet Cable , Coaxial Cable , Optical Fiber Cable
2. Wireless: Bluetooth , Infrared , Wi-Fi

Types of Networks

• PAN  ( 10 m )  , 1 Computer
• LAN ( 100 m ) , 2 or more Computer
• CAN ( Campus Area Network )
• WAN ( two or more computers at distant places.)

Networking Devices 

• Modem: to connect computer to the internet over existing telephone line.
• Hub: to connect multiple computers & devices by using cables.
• Switch: Similar to hub, but offer greater performance
• Repeater : used  to regenerate a signal.
• Router: used to connect two different networks.
• Gateway: acts as an entrance to another network using different protocols.
• Bridge : Similar to repeater with add-on functionality of filtering content.

Networking Terminology

• Internet : A global wide area network that connects computers across the world.
• Intranet: A computer network with in an organization.
• Bandwidth: The amount of data that can be transmitted in a fixed amount of time.
• ISP : Service provider that provides internet connection.
• Website: A collection of webpages containing images , videos and texts.
• Web Portal: A gateway or entrance to the access of information.
• Web Page: A digital page which contains text , hyperlink, videos , audios, images, tables etc..
• Home Page: First page of website.
• Link: a line or channel to connect two devices.
• Hyperlink: A link that connects one webpage to another webpage.
• URL: Unique Address of a webpage or a website.
• IP Address: A unique (32 bit) set of numbers, which is provided to each computer by IETF.
• Domain Name: A unique name given to each website.
• TCP/IP: A suite of communication protocols used to connect various computers on the internet.
• TCP: used for a reliable data transmission over the network.
• IP: Provides a sequence numbers to each data packets so that they can reach their destination.
• HTTP: A protocol that defines what actions web servers and browsers should take in response to various commands.
• FTP: A protocol to exchange files between two or more computers on the internet.

 

 

Python : Python is a programming language which takes input, process and provide output.

• Features of Python: 
  •  Simple & Interactive
  • Platform Independent
  • Case Sensitive
  • Object Oriented
  • Interpreted Language
  • Uses variables without declaration

Working Mode of Python

• Interactive mode  ( the interpreter executes the statements one by one )
• Script Mode ( Displays the results of expressions )

Types of Commands in Interactive Mode:

• print ( ) function  : to print output.
• " , " ( comma ) : to print the next value after a space.
• "\t" (tab ) : to print the new value in the next line.
• type ( ) function: to return the data type of a value.
• Input ( ) function: to store a value in a variable.

Variables:  a , b , c  etc. are variables used to store the values.

Data Types in Python:

•  int : used when you have to work with whole numbers ( +ve or -ve ) , Example:  1500 , -1986
• float : represents floating point values. Example : 709 , 789 , 17.234
• string : Represents a collection of characters enclosed within single or double quotes. Example: Python_Language
• bool: 124<987

Arithmetic Operators in Python:

• Unary Operators : They work on a single operand. Ex. (  a=10 , a=-10 )
• Binary Operators: They work on two operands. Ex. ( a=30 , b =20 )
• Addition (+) : to add data values .  (Ex. , 30+20=50)
• Subtraction (-) : to find difference of the data value ( Ex.  100-30=70 )
• Multiply (*) : to find product of the data value ( Ex. 10*2= 20 )
• Division ( /) : to divide the numbers and give results in decimal form. ( Ex. 10/4=2.5)
• Integer Division (//): to divide the numbers and give results in integer form.( Ex. 10//4=2)
• Modulus ( % ): to divide the numbers and give the remainder. ( Ex. 10%3=1 )
• Exponential ( **): to find the powers of the numbers. ( 3**4=81 )

Precedence of operators:

• ( )  : Parenthesis
• **  : Exponentiation
• +X ,-X : +Unary , -Unary
• * , / , // , % : Multiplication, Division, Floor Division, Modulus
• + ,- : Binary Addition  , Subtraction
• < , > , <= , = , = = , != : Rational Operators
• not and or : Boolean /Logical operators

Conditional Statements:

if statement

if << condition>:

statements set

Example of Program: 

a=int ( input ( input ("Enter a number :")

b=int ( input ( input ("Enter another number :"))

if  a==b:

print ( " The numbers are equal ")

Output

Enter a number :34

Enter another number :34

The numbers are equal

 

if...else statement

if << condition>:

statements set 1

else

statements set 2

Example of Program: 

a=int ( input ( input ("Enter the first number :")

b=int ( input ( input ("Enter the second number :"))

if  a>b:

print ( a, "is greater than" , b )

else:

print ( b, " is greater than " a )

Output

Enter the first number :456

Enter the second number :234

456 is greater than 234

Iterative Statements : The statements that keep repeating themselves as long as a given condition. These are slso called Repetitive statements or looping statements.

In Python , there are two types of Iterative statements:

for : used when we are sure about how many times a loop body will be executed. Also known as definite loop.

The syntax for using the for loop is:

for < variable > in <

• while :