CompTIA Net+ Module 3

Question 1

What is instantaneous data transmission ?

Answer 1

Question 2

What is serial data transmission ?

Answer 2

• Method of transmitting data one bit at a time over a communication channel.
• Types
• Synchronous = Data sent in continuous stream, synchronised by clock signal shared btw sender and receiver
• Asynchronous = Data sent one byte at a time, with start & stop bits added to indicate the beginning and end of each bytes.

Question 3

What is Synchronous and Asynchronous data transmission ?

Answer 3

Question 4

What is Parallel Data Transmission ?

Answer 4

• Method of transmitting multiple bits of data simultaneously across multiple channels.
• Higher speeds, short distance
• CPU and Memory (Internal Buses)

Question 5

What is baseband transmission?

Answer 5

Transmits signals over a channel without modulating to higher frequencies.

• Occupies entire bandwidth.

Question 6

What is Broadband Transmission ?

Answer 6

• a high-speed data transmission method using a wide frequency range to send multiple signals (voice, video, data) simultaneously over a single medium

Question 7

What is a channel in communication systems ?

Answer 7

• Pathway for transmitting information.
• Physical Channel: eg twisted pair, coaxial cable, fiber optic).
• Logical Channel: A shared medium divided into multiple virtual channels (e.g., time-division multiplexing, frequency-division multiplexing).

Question 8

What is contention-based media access ?

Answer 8

Question 9

What is controlled media access ?

Answer 9

• refers to the process of regulating how multiple devices share a common communication medium to avoid collisions and ensure efficient data transmission

Question 10

What is multiplexing ? (controlled media access)

Answer 10

• Media access method that takes multiple signals and combines them over a shared medium.
• Time Division Multiplexing(TDM)
• Frequency Division Multiplexing (FDM)
• Code Division Multiplexing(CDM)
• Orthogonal Frequency Division Multiplexing(OFDM)

Question 11

What is Time Division Multiplexing ?

Answer 11

• Multiple signals share the same frequency band but are transmitted in diff time slots.

Question 12

What is Frequency Division Multiplexing ?

Answer 12

• is a technique that splits a single, wide communication channel into multiple narrower, non-overlapping frequency bands, allowing several signals (like radio stations, TV channels, or phone calls) to travel simultaneously over the same physical medium without interfering with each other

Question 13

What is Multiplexer (Mux) ?

Answer 13

• Is a device that combines multiple data signals from different sources and sends them over a single communication channel

Question 14

What is Polling ? (Controlled Media Access)

Answer 14

• A technique where a central device continuously checks other devices to see if they have data to send
• variation of polling is Demand Priority.
• Nodes signals state, data to transmit or not

Question 15

What is framing ?

Answer 15

• Framing is the process of dividing a stream of data into manageable, discrete units called frames.
• Key Functions:

Data Encapsulation: Wraps data in headers and trailers.

Error Detection/Correction: Adds checksums or CRCs.

Addressing: Includes source and destination addresses.

Flow Control: Regulates data transmission rate.

Question 16

In which order does the OSI model operate ?

Answer 16

• Sending Data = Descending order (Applications to Physical)
• Receiving Data = Ascending order (Physical to Applications)

Question 17

What is CSMA-CD ?

Answer 17

Question 18

What is CSMA-CA

Answer 18

• CSMA/CA stands for Carrier Sense Multiple Access with Collision Avoidance. It’s a network protocol used primarily in wireless networks to manage how data packets are transmitted over a shared communication medium, aiming to avoid collisions rather than detect them.

Question 19

What is Contention Domain ?

Answer 19

Question 20

What is Broadcast Domain ?

Answer 20

• Is a part of a network where any device can directly send broadcasts to all other devices within the same segment.

Question 21

Does Contention domain fall under Broadcast domain ?

Answer 21

Question 22

What is a clock cycle ?

Answer 22

• clock cycle = single electronic pulse of a CPU.
• CPU perform basic operation like writing data.
• Duration of a clock cycle = inverse of the clock frequency.
• In simpler terms, think of it as the heartbeat of the CPU, dictating how fast it can process instructions.

Modern CPUs can complete millions or even billions of clock cycles per second, which is why their speeds are often measured in megahertz (MHz) or gigahertz (GHz).

Question 23

How are frequency, bandwidth and digital signals related ?

Answer 23

• Bandwidth in digital communication is related to data rate (bps).
• Digital Signals transmitted using modulated carrier wave.
• High data rate req high bandwidth, more frequencies to represent rapidly changing 0’s and 1’s

Question 24

Why are higher frequencies used as carriers in modulation instead of lower frequencies.

Answer 24

• Efficient use of spectrum: more bandwidth at higher end of electromagnetic spectrum.
• Practical antenna size: Antenna size needs to be roughly the size of the wavelength of the signal.
• Lower freq travel further with less interference(less bandwidth and more noise) but higher frequency allows for more bandwidth and data capacity.

Question 25

What is modulation ?

Answer 25

- Is a technique of superimposing a msg signal onto a carrier signal(Higher frequency) to transmit msg over longer distances.

Question 26

List 3 types of modulation for analog signals.

Answer 26

- Frequency Modulation (FM): Changes the frequency of the carrier wave according to the msg signal - Amplitude Modulation (AM): Changes the amplitude of the carrier wave according to the msg signal - Phase Modulation (PM): Alters the phase of the carrier wave in relation to the msg signal

Question 27

What bandwidth are assigned for fm radios in Australia and how do they work ?

Answer 27

- 200 kHz - Eg, if FM station broadcast at centre frequency 100 MHz. - Bandwidth = 200kHz (span from 99.9 MHz to 100.1 MHz)

Question 28

What is stereo ?

Answer 28

- Stereo (stereophonic sound) is a method of sound reproduction that creates the illusion of multi-directional audio perspective by using two or more independent audio channels, typically played through two speakers (left and right).

Question 29

What is a signal ?

Answer 29

- Data translated into electromagnetic information that can be transmitted and received by communiation devices. - an electric, electromagnetic, or optical impulse (voltage, current, or light wave) that carries data across a network, acting as the physical representation of information

Question 30

What is analog signal ?

Answer 30

- A signal that carries data in a continuous waveform via either electromagnetic energy.

Question 31

What is a codec ?

Answer 31

- A codec ("coder-decoder" or "compressor-decompressor") is a software algorithm that: - Encodes (compresses) data into a compact format for storage or transmission. - Decodes (decompresses) data back to its original form. Types of Codecs: - Audio Codecs: Compress audio files (e.g., MP3, AAC). - Video Codecs: Compress video files (e.g., H.264, VP9). - Image Codecs: Compress image files (e.g., JPEG, PNG). - Text Codecs: Compress text data (e.g., ZIP, gzip).

Question 32

List the modulation techniques for digital signals.

Answer 32

Question 33

In what contexts are Kilobit (kb) and Kilobyte (KB) used?

Answer 33