Networks and Communications

What is a computer network?

A collection of interconnected devices like computers, servers, routers, etc., allowing the sharing of data and resources.

What are the advantages of computer networks?

Resource sharing, communication and collaboration, centralized management, increased security, and scalability.

What is one disadvantage of computer networks?

Complexity in setup and maintenance, requiring specialized knowledge.

How do computer networks enhance security?

They centralize and control access to data, reducing the risk of data breaches.

What is data mining?

Analyzing network data to extract useful information for optimization.

What is a point-to-point connection?

A communications connection between two endpoints.

What is a key advantage of point-to-point communication?

Provides a dedicated communication channel ensuring reliable communication.

What is the disadvantage of point-to-point communication?

It can be expensive and less flexible due to dedicated communication links.

What are the components of data communication?

Sender, receiver, medium, protocol, and message.

What are the two types of signals used in data communications?

Analog signals and digital signals.

What process converts digital signals into analog signals?

Digital-to-analog conversion (DAC).

What is the latency in data transmission?

The time it takes for data to travel from one point to another.

What is serial transmission?

Sending data one bit at a time over a single channel.

What is parallel transmission?

Sending multiple data bits simultaneously over multiple channels.

What is asynchronous transmission?

Data transmitted one byte at a time without requiring a clock signal.

What mechanism is used to detect errors in asynchronous transmission?

Parity check.

What is a simplex transmission?

A one-way communication where one side sends and the other receives.

What is the purpose of modulation?

Converting digital data into analog signals for transmission.

What is amplitude modulation (AM)?

A technique where the amplitude of the carrier wave is varied to encode information.

What defines the transmission rate?

The speed at which data can be transmitted over a network.

What is noise in data communication?

Unwanted electrical energy that interferes with the desired signal.

What does 'attenuation' refer to?

The gradual loss of signal strength as it travels through a medium.

What are communication protocols?

Rules that govern the exchange of data between devices on a network.

Name a common communication protocol.

Transmission Control Protocol / Internet Protocol (TCP/IP).

What is an IP address?

A numerical label assigned to each device for communication over a network.

What is the difference between a public and private IP address?

Public IPs are accessible on the internet; private IPs are used within a private network.

Define dynamic IP address.

An IP address that changes periodically.

What is a static IP address?

An IP address that remains constant over time.

What is encapsulation in data packets?

The process of adding headers and trailers to data packets.

What is the advantage of fiber optic cables?

Higher bandwidth and less susceptibility to interference than metal cables.

What is the disadvantage of a fiber optic cable?

It is more expensive over short distances and more fragile.

What is frequency-division multiplexing (FDM)?

Assigning different frequency bands to multiple data streams.

What is time-division multiplexing (TDM)?

Transmitting different data streams in alternating time slots.

What is packet switching?

Dividing messages into packets before transmission, allowing efficiency and rerouting.

Define datagram.

A self-contained unit of data transmitted over a network.

What is an error in data communication?

Bit errors, frame errors, packet loss, and delay are common types of errors.

What technique helps prevent network congestion?

Traffic shaping.

What is a digital signature?

A cryptographic technique used to verify the authenticity of a digital document.

What is a multiplexer (Mux)?

A device allowing multiple signals to be transmitted over a single channel.

What is an example of a wireless protocol?

Bluetooth.

What are shielding techniques used for?

To protect sensitive components from electromagnetic interference (EMI).

What does 'secure protocols' like HTTPS ensure?

It secures communications by encrypting data and verifying identities.

What is the function of a modulator?

It converts digital data into analog signals.

What is the definition of 'signal propagation'?

The process of transmitting a signal from one point to another through a medium.

What are the two fundamental categories of transmission modes?

Serial and parallel.

What is the purpose of error detection and correction codes?

To ensure data is transmitted accurately and errors are corrected.

What is the impact of interference on signal transmission?

It can cause errors or data corruption, leading to loss of data.

What does bandwidth refer to?

The maximum amount of data that can be transmitted over a network in a given time.

How is transmission time calculated?

Transmission time = message size / bandwidth.

What is the difference between bit rate and baud rate?

Bit rate measures the number of bits per second; baud rate measures the number of signal units per second.

What is infrared used for in data transmission?

For short-range communication, like remote control devices.

What is digital-to-analog conversion (DAC)?

Converting digital signals into analog signals.

What is an echo check used for?

To detect errors by sending data back to the sender for comparison.

What is a major disadvantage of circuit switching?

Inefficient use of the communication channel when it is idle.

What is the function of a demodulator?

To convert analog data back into digital data.

What is the primary role of the header in a data packet?

To contain routing information for the source and destination.

What is payload in the context of data packets?

The actual data being transmitted.

How does signal distortion affect data communication?

It can cause alterations that lead to errors in data transmission.

What is the significance of encryption?

It transforms data into a secure format that is unreadable without a key.

What happens during data sampling?

Selecting a subset of data for analysis from a larger dataset.

What is the function of email protocols like SMTP?

To govern how email messages are formatted and transmitted.

What does data integrity refer to?

The completeness, accuracy, and consistency of data being sent.

What do you need a static IP address for?

For hosting servers, remote access, security, and networked printers.

What is a wireless application protocol (WAP)?

Used for accessing web pages on mobile devices.

How does congestion control contribute to network efficiency?

It prevents congestion and maintains performance by managing traffic.

What is the difference in application between FDM and TDM?

FDM is for multiple continuous signals; TDM is for fewer signals requiring full bandwidth.

What are the types of signal modulation?

Amplitude modulation, frequency modulation, and phase modulation.

What is the main challenge in packet switching?

Protocols can be complex and may incur initial implementation costs.

What does a trailer in data packets typically contain?

A checksum to verify the data's integrity after transmission.

What is 'Network Bandwidth'?

The maximum amount of data that can be transmitted over a network in a specified period.

How does one identify different components in data communications?

Sender, receiver, medium, protocol, and message.

What technique is used to maintain data integrity?

Error detection and correction codes.

What does the term 'Transmission Control Protocol' refer to?

A protocol ensuring accurate and complete data transmission.

What role does a checksum play?

It detects errors in transmitted data.

What is the purpose of using shielding in cables?

To reduce the effects of electromagnetic interference.

What is a consequence of frame errors?

Loss or corruption of one or more bits in a frame.

CRC (Cyclic Redundancy Check)

An algorithm used to calculate checksums in computer networks.

Ethernet cables

A type of networking cable used to connect devices together in a wired local area network.

Twisted Pair

Cheapest but has slow transmission rates and suffers from electronic interference. The conductors are twisted together for the purpose of cancelling out EMI.

Coaxial Cable

High quality, well insulated cable which can transmit data much faster and more accurately than twisted pair.

Unshielded twisted pair (UTP)

The most popular and is generally the best option for business networks. Each pair is twisted with a different number of twists per inch to help eliminate interference. Easiest to install.

Shielded Twisted Pair (STP)

Each of the two copper wires that are twisted together are coated with an insulating coating that functions as a ground for the wires. It is more expensive and harder to handle.

Microwave systems

They use the earth’s atmosphere at the medium through which to transmit. These systems are used for high-volume as well as long-distance communication of both data and voice in the form of electromagnetic waves.

Satellite systems

Although establishing a satellite is costly it has become the most popular and cost effective method for moving large quantities of data over long distances.

What is an advantage of satellite communications?

The vast area that can be covered by a single satellite

Fibre optics

Dominant communications medium because of its high transmission volume, low error rate and message security. Free of interference and the light pulses travel for miles without losing strength.

Advantages of Fibre Optic Cable

1. Greater bandwidth than metal cables

2. Less susceptible to interference

3. Data can be transmitted digitally

4. Lower attenuation

Disadvantages of fibre optic cable

1. Expensive over a short distance

2. Fibres can be broken or have transmission losses when wrapped around curves of only a few cm radius

3. Requires highly skilled installers

Attenuation

The gradual loss of signal strength as it travels through a medium such as a cable or wireless transmission.

How can attenuation occur in copper wires and how can it be mitigated?

This happens due to resistance in the copper wires which causes the signal to weaken over long distances.

Solution → Using signal repeaters to amplify the signal

How can attenuation occur in wireless networks

This occurs due to obstacles such as walls and other physical barriers that interfere with the signal.

Wireless transmission

Refers to the transfer of data between devices without the use of physical cables or wires. Devices communicate with each other using radio waves and infrared signals.

Wi-Fi

A wireless networking technology that uses radio waves to connect devices to the internet or a local network.

Bluetooth

A wireless technology that enables devices to communicate with each other over short distances.

How does infrared wireless transmission work? What is it often used for?

Uses light waves to transfer data between devices. Often used in remote controls for televisions.

Satellite Transmission Application

Television distribution

• A network provides programming from a central location.

• Direct broadcast satellite (DBS)

Data integrity

This refers to the overall completeness, accuracy and consistency of data.

When must data integrity be imposed and how can it be achieved?

When sending data through a network. This can be achieved by using error checking and correction protocols

Encryption

The process of transforming data into a code that is unreadable without the appropriate decryption key.

Hashing

The process of generating a unique identifier (hash) for a piece of data. The hash can be used to verify that the data has not been modified during transmission.