A computer network is a collection of interconnected computers that allows them to communicate and share resources, data, and applications. 

Data Communication is defined as exchange of data between two devices via some form of transmission media such as a cable, wire or it can be air or vacuum also.

Components- 

1) Message

2) Sender

3) Receiver

4) Transmission Medium

5) Set of Rules (Protocols)

Distributed processing in computer networks involves multiple interconnected computers collaborating to solve a task or process data. This method enhances performance, fault tolerance, and scalability. Tasks are divided among the networked computers, with each node processing its portion independently and exchanging data when necessary.

Used in- 

1) Distributed databases

2) Cloud computing

3) Content Delivery Networks (CDNs)

A network is two or more devices connected by a link, which is a communication pathway that transfers data between devices. Devices can be computers, printers, or any other device that can send and receive data. For visualization, imagine any link as a line drawn between two points.

Features- 

1) Point-to-Point

2) Multipoint

3) Star

4) Mesh

Connections- 

1) Point-to-Point

2) Multipoint

A network topology is the arrangement with which computer systems or network devices are connected to each other. It defines both the physical and logical aspects of the network, which may be the same or different for a particular network.

Types- 

1) Point-to-Point

2) Bus

3) Star

4) Tree

5) Ring

6) Mesh

7) Daisy Chain

8) Hybrid

Transmission mode is the method by which data is transferred between devices. It is also known as communication mode and is defined by the physical layer of the network.

It determines the direction of data flow, which can be-

1) Simplex mode

2) Half-duplex mode

3) Full-duplex mode

A computer network is a collection of interconnected computers that allows them to communicate and share resources, data, and applications.

Categories- 

1) LAN (Local Area Network)

2) MAN (Metropolitan Area Network)

3) WAN (Wide Area Network)

4) PAN (Personal Area Network)

5) CAN (Campus Area Network)

1) Physical Layer

2) Data Link Layer

3) Network Layer

4) Transport Layer

5) Session Layer

6) Presentation Layer

7) Application Layer

1) Application Layer

2) Transport Layer

3) Internet Layer

4) Network Access Layer

Attenuation refers to the loss of signal strength as it travels through a medium, caused by the resistance of the medium. Amplifiers are used to boost the attenuated signal, restoring it to its original strength and compensating for the loss.

Signal distortion refers to the alteration of the signal's shape or form, typically observed in composite signals composed of various frequencies. Each frequency component propagates at a different speed through the medium, causing them to arrive at the destination at varying times. This disparity in arrival times results in phase differences between the sender's and receiver's ends, leading to signal distortion.

Noise is an unwanted signal that interferes with the original message signal, corrupting its parameters and altering the message. It typically enters the communication process at the channel or receiver. Noise lacks a pattern, constant frequency, or amplitude, making it random and unpredictable. Measures are employed to reduce noise, but complete elimination is impossible.

Common noise examples include:

• Hiss in radio receivers

• Buzz during phone conversations

• Flicker in television receivers 

Throughput is the measure of the amount of data transmitted over a network, interface, or channel during a specified time period. It's also referred to as effective data rate or payload rate.

Propagation speed

It is the distance a signal or bit travels through a transmission medium in one second. It is typically measured in meters per second (m/s) or kilometers per second (km/s). The propagation speed of an electromagnetic signal depends on the medium through which it is traveling and the frequency of the signal.

Propagation time 

It is the time required for a signal or bit to travel from one point to another. It is calculated using the following formula:

Propagation Time =Distance / Propagation Speed

Wavelength is a measure of the distance a signal can travel in one period. It is the distance between corresponding points on a wave. The SI unit of wavelength is the meter (m).

Wavelength =Propagation Speed / Frequency