# Z3D153 Vol 1 Unit 3

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Quizzes Created: 6 | Total Attempts: 1,513
Questions: 35 | Attempts: 102

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• 1.

### What are three general categories used to produce modulation in radio frequency (RF) transmission today?

• A.

Binary amplitude shift keying, frequency shift keying, and phase shift keying.

• B.

Pulse amplitude, pulse width, and pulse position.

• C.

Amplitude, frequency, and phase.

• D.

Analog, digital and shift keying.

C. Amplitude, frequency, and pHase.
Explanation
The three general categories used to produce modulation in radio frequency (RF) transmission today are amplitude, frequency, and phase. Modulation is the process of varying one or more properties of a carrier signal in order to transmit information. Amplitude modulation (AM) involves varying the amplitude of the carrier signal to encode the information. Frequency modulation (FM) involves varying the frequency of the carrier signal. Phase modulation (PM) involves varying the phase of the carrier signal. These three categories are commonly used in modern RF transmission to encode and transmit data.

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• 2.

### When the modulating signal and carrier signal are combined within a modulator, the output signal contain

• A.

Modulating signal, upper sideband, and lower sideband.

• B.

Carrier, upper sideband, and lower sideband.

• C.

Upper sideband and modulating signal.

• D.

Carrier and modulating signal.

B. Carrier, upper sideband, and lower sideband.
Explanation
When the modulating signal and carrier signal are combined within a modulator, the output signal contains the carrier signal, as well as the upper sideband and lower sideband. The carrier signal represents the original frequency of the carrier wave, while the upper and lower sidebands represent the frequency components that are shifted above and below the carrier frequency due to modulation. This combination of signals allows for the transmission of information through the modulation process.

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• 3.

### What factor determines the spacing of the sidebands in an amplitude modulated signal?

• A.

Amplitude of the modulating signal.

• B.

Frequency of the modulating signal.

• C.

Amplitude of the carrier signal.

• D.

Frequency of the carrier signal.

B. Frequency of the modulating signal.
Explanation
The spacing of the sidebands in an amplitude modulated signal is determined by the frequency of the modulating signal. In amplitude modulation, the modulating signal affects the amplitude of the carrier signal, resulting in the creation of sidebands. The frequency of the modulating signal directly influences the distance between these sidebands. A higher frequency modulating signal will lead to sidebands that are closer together, while a lower frequency modulating signal will result in sidebands that are further apart. Therefore, the frequency of the modulating signal is the factor that determines the spacing of the sidebands.

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• 4.

### The amount of effect or change that the intelligence has on the carrier in an amplitude modulated signal is expressed as the

• A.

Percent of modulation.

• B.

Modulation index.

• C.

Bandwidth.

• D.

Deviation.

A. Percent of modulation.
Explanation
The amount of effect or change that the intelligence has on the carrier in an amplitude modulated signal is expressed as the percent of modulation. This indicates the percentage of variation in the carrier signal caused by the modulation. A higher percent of modulation indicates a stronger influence of the intelligence on the carrier signal, while a lower percent of modulation indicates a weaker influence. The modulation index, bandwidth, and deviation are not specifically used to express the amount of effect or change in an amplitude modulated signal.

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• 5.

### Reducing modulation to less than 100 percent gives

• A.

More total power.

• B.

A reduction in carrier power.

• C.

No reduction in carrier power.

• D.

A reduction in carrier and sideband power.

C. No reduction in carrier power.
Explanation
When reducing modulation to less than 100 percent, there is no reduction in carrier power. Modulation refers to the process of varying the amplitude, frequency, or phase of a carrier signal to transmit information. When modulation is less than 100 percent, it means that the variation in the carrier signal is not reaching its maximum potential. However, this does not affect the power of the carrier signal itself. The carrier power remains the same regardless of the level of modulation.

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• 6.

### The output of the oscillator in a frequency modulation (FM) modulator increases in frequency with each

• A.

Positive half cycle of the carrier.

• B.

Negative half cycle of the carrier.

• C.

Positive half cycle of the modulating signal.

• D.

Negative half cycle of the modulating signal.

C. Positive half cycle of the modulating signal.
Explanation
In frequency modulation (FM), the frequency of the carrier signal is varied according to the amplitude of the modulating signal. The modulating signal is a low-frequency signal that controls the frequency of the carrier signal. In this case, the output of the oscillator in the FM modulator increases in frequency with each positive half cycle of the modulating signal. This means that as the modulating signal's amplitude increases during the positive half cycle, the frequency of the carrier signal also increases.

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• 7.

### A 5 kilohertz (kHz) modulating signal has enough peak voltage to cause a deviation of 15 kHz. What is the modulation index?

• A.

5.

• B.

3.

• C.

.5

• D.

.3

B. 3.
Explanation
The modulation index is a measure of how much the carrier signal is modulated by the modulating signal. In this question, the modulating signal has a frequency of 5 kHz and causes a deviation of 15 kHz. The modulation index can be calculated by dividing the deviation by the frequency of the modulating signal. In this case, the modulation index is 15 kHz / 5 kHz = 3. Therefore, the correct answer is 3.

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• 8.

### What is the narrow frequency band between adjacent stations used to prevent frequency modulated sidebands from overlapping?

• A.

Space.

• B.

Guard band.

• C.

Buffer zone.

• D.

Prevention field.

B. Guard band.
Explanation
A guard band is a narrow frequency band that is placed between adjacent stations to prevent frequency modulated sidebands from overlapping. This ensures that there is no interference between the signals of neighboring stations, allowing for clear and uninterrupted communication. The guard band acts as a buffer zone, preventing any overlap and maintaining the integrity of each station's signal.

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• 9.

• A.

Easier detection.

• B.

Smaller bit error rate.

• C.

Better signal-to-noise ratio.

• D.

Higher data rates within a given bandwidth.

D. Higher data rates within a given bandwidth.
Explanation
Adding more phase shifts allows for more bits to be represented in a given amount of time, which increases the data rate. By increasing the number of phase shifts, more information can be encoded in each symbol, allowing for a higher transmission rate within a limited bandwidth. This advantage is particularly important in communication systems where maximizing data rates is a priority.

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• 10.

### What is the first step in the pulse code modulation process?

• A.

Discrete amplitudes are assigned to the sampling pulses.

• B.

A binary code number is assigned to the sample.

• C.

The quantizer limits the amplitude of the pulses.

• D.

The analog signal is band limited.

D. The analog signal is band limited.
Explanation
The first step in the pulse code modulation process is to band limit the analog signal. Band limiting refers to the process of restricting the frequency range of the analog signal to a certain bandwidth. This is done to ensure that the signal can be accurately sampled without any loss of information. By limiting the bandwidth, any frequencies outside the desired range are eliminated or attenuated, allowing for a more efficient and accurate conversion of the analog signal into a digital representation.

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• 11.

### Quantization in the pulse code modulation process?

• A.

Converting a continuous time signal into a discrete time signal.

• B.

Ensuring the input to the sampler never exceeds maximum frequency.

• C.

Placing an infinite number of amplitude values to a finite number of values.

• D.

Limiting the highest and lowest frequency encoded before it goes to the sampler.

C. Placing an infinite number of amplitude values to a finite number of values.
Explanation
In the pulse code modulation process, quantization refers to the process of converting a continuous time signal into a discrete time signal. This is achieved by placing an infinite number of amplitude values to a finite number of values. Quantization helps in reducing the amount of data needed to represent the signal, making it more efficient for transmission and storage. By limiting the number of amplitude values, quantization introduces a small amount of error called quantization error, which is the difference between the original signal and the quantized version.

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• 12.

### In asynchronous transmissions, what bit is used by the receiving device to verify that the transmission was received correctly?

• A.

Control.

• B.

Parity.

• C.

Start.

• D.

Stop.

B. Parity.
Explanation
Parity is used by the receiving device in asynchronous transmissions to verify that the transmission was received correctly. Parity is a simple error-checking technique where an extra bit, either 0 or 1, is added to each transmitted character. The value of this extra bit is determined based on the number of 1s in the character. The receiving device then checks if the number of 1s in the received character matches the expected parity. If they don't match, an error is detected, indicating that the transmission was not received correctly.

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• 13.

### If an error should occur, what transmission is lost in an synchronous transmission?

• A.

One character.

• B.

Block of data.

• C.

A parity bit.

• D.

A stop bit.

B. Block of data.
Explanation
In synchronous transmission, data is sent in blocks rather than individual characters. Therefore, if an error occurs during transmission, it is the block of data that is lost, not just one character.

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• 14.

### The significance the amount of ones have in a data bit pattern when using vertical redundancy check (VRC) is that it determines

• A.

Parity.

• B.

Transmission rate.

• C.

Whether transmission is synchronous or asynchronous.

• D.

Whether transmission is in American Standard Code for Information Interchange (ASCII) format.

A. Parity.
Explanation
The significance of the amount of ones in a data bit pattern when using vertical redundancy check (VRC) is that it determines parity. Parity is a form of error checking where an extra bit is added to a data transmission to ensure that the number of ones in the transmission is either even or odd. By counting the number of ones in the data bit pattern, the receiver can check if the transmission has an even or odd parity. This helps in detecting errors during transmission.

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• 15.

### What two error detection methods, when used together, are 98 percent effective in detecting errors?

• A.

Longitudinal redundancy check (LRC) and checksum.

• B.

Checksum and cyclic redundancy check (CRC).

• C.

Vertical redundancy check (VRC) and CRC.

• D.

VRC and LRC

D. VRC and LRC
Explanation
VRC (Vertical Redundancy Check) and LRC (Longitudinal Redundancy Check) are two error detection methods that, when used together, are 98 percent effective in detecting errors. VRC checks for errors by adding a parity bit to each character in a data block, while LRC checks for errors by adding a parity bit to each block of characters. By using both methods, errors can be detected with a high level of accuracy.

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• 16.

### When using forward error control as a method of error correction, where does error correction take place?

• A.

Receiving end.

• B.

In the oscillator.

• C.

Transmitting end.

• D.

In the primary buffers.

A. Receiving end.
Explanation
Forward error control is a method of error correction that involves adding redundancy to the transmitted data in order to detect and correct errors at the receiving end. This means that the error correction takes place at the receiving end, where the received data is checked for errors and any errors are corrected using the redundant information. The transmitting end is responsible for adding the redundancy to the data, but the actual error correction occurs at the receiving end.

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• 17.

### In telecommunications cable, the "tip" or "primary" wire color group order is

• A.

White, blue, green, yellow, and violet.

• B.

Blue, orange, green, brown, and slate.

• C.

White, red, black, yellow, and violet.

• D.

Blue, green, yellow, red, and orange.

C. White, red, black, yellow, and violet.
Explanation
The correct answer is white, red, black, yellow, and violet. This is the correct order for the "tip" or "primary" wire color group in telecommunications cable.

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• 18.

### Two types of network cables are

• A.

Straight through and crossover.

• B.

Straight through and flip/flop.

• C.

High and low baud.

• D.

"n" and "g".

A. Straight through and crossover.
Explanation
The correct answer is straight through and crossover. Straight through cables are used to connect devices of different types, such as a computer to a switch or a router. Crossover cables, on the other hand, are used to connect devices of the same type, such as a computer to another computer or a switch to another switch. These cables have their transmit and receive wires crossed over in order to facilitate communication between similar devices.

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• 19.

### An optical transmitter is compromised of

• A.

Positive intrinsic negative and avalanche photodiodes.

• B.

Repeaters, regenerators, and optical amplifiers.

• C.

A driver, optical source, and fiber optic pigtail.

• D.

A light detector and output circuits.

C. A driver, optical source, and fiber optic pigtail.
Explanation
The correct answer is "a driver, optical source, and fiber optic pigtail." An optical transmitter is a device that converts electrical signals into optical signals for transmission through fiber optic cables. A driver is used to provide the electrical signals, an optical source generates the optical signals, and a fiber optic pigtail is used to connect the transmitter to the fiber optic cable. This combination allows for the transmission of data through optical fibers.

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• 20.

### What is the bandwidth of multimode step-index optical fiber cable?

• A.

10 MHz -100 MHz/km.

• B.

100 MHz -200 MHz/km.

• C.

200 MHz - 1000 MHz/km.

• D.

Up to 50 GHz/km.

A. 10 MHz -100 MHz/km.
Explanation
The bandwidth of a multimode step-index optical fiber cable is typically measured in terms of MHz/km. This refers to the range of frequencies that can be transmitted through the cable over a kilometer of distance. In this case, the correct answer is 10 MHz - 100 MHz/km, indicating that the cable can support frequencies ranging from 10 MHz to 100 MHz over a distance of 1 kilometer.

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• 21.

### Which type of cable is the hardest to splice?

• A.

• B.

Multimode step index fiber.

• C.

Unshielded twisted pair.

• D.

Single mode fiber.

D. Single mode fiber.
Explanation
Single mode fiber is the hardest to splice because it has a smaller core diameter compared to multimode fibers. This smaller core diameter results in a higher transmission capacity and longer transmission distances, but it also makes the splicing process more challenging. The smaller core size requires more precision and expertise to align the fibers accurately during the splicing process. Additionally, single mode fibers often have a more complex refractive index profile, making the splicing process even more difficult.

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• 22.

### A short section of single fiber cable that has a connector at each end is called a

• A.

Pigtail.

• B.

Jumper.

• C.

Patch cord.

• D.

Breakout cables.

C. Patch cord.
Explanation
A short section of single fiber cable that has a connector at each end is called a patch cord. A patch cord is used to connect devices or equipment together, typically in a local area network (LAN) or data center environment. It is often used to connect network switches, routers, servers, or other network devices. The connectors on each end of the patch cord allow for easy and quick connection and disconnection of devices.

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• 23.

### What allows transportation of all active virtual LANs (VLAN) between switches using a single physical link?

• A.

Trunks.

• B.

Frames.

• C.

• D.

Ports.

A. Trunks.
Explanation
Trunks allow the transportation of all active virtual LANs (VLAN) between switches using a single physical link. A trunk is a point-to-point link that carries multiple VLANs simultaneously, allowing for efficient and effective communication between switches. By using trunks, multiple VLANs can be transmitted over a single physical link, reducing the need for multiple physical connections and simplifying network management.

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• 24.

### Which device has multi port connectivity that directs data between nodes on a network?

• A.

Bridge.

• B.

Router.

• C.

Gateway.

• D.

Repeater.

B. Router.
Explanation
A router is a device that has multi-port connectivity and is responsible for directing data between nodes on a network. It acts as a central hub, receiving data packets from various devices and determining the most efficient path for the data to reach its destination. Routers use routing tables to make these decisions, ensuring that data is delivered accurately and efficiently. Unlike bridges, gateways, and repeaters, routers have the capability to connect multiple networks together and provide interconnectivity between them.

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• 25.

### Which routing protocol do Internet backbones use?

• A.

Open shortest path first (OSPF).

• B.

Border gateway protocol (BGP).

• C.

Routing information protocol (RIP).

• D.

Enhanced interior gateway routing protocol (EIGRP).

B. Border gateway protocol (BGP).
Explanation
Internet backbones use Border Gateway Protocol (BGP) as their routing protocol. BGP is specifically designed for large-scale networks and is used to exchange routing information between different autonomous systems (AS). It allows routers in different ASs to communicate and exchange information about the best paths for routing traffic. BGP is widely used in the Internet backbone to ensure efficient and reliable routing of data packets across different networks and ASs.

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• 26.

### Virtual private networks (VPNs) allow the AF to extend network resources across a/an

• A.

Department of Defense network.

• B.

Air Force network.

• C.

Local area network.

• D.

Public network.

D. Public network.
Explanation
Virtual private networks (VPNs) allow the AF to extend network resources across a public network. This means that the AF can securely access and utilize network resources from any location, using the internet as the medium. By encrypting data and creating a secure tunnel, VPNs ensure the confidentiality and integrity of information transmitted over the public network. This enables the AF to connect to remote networks, such as the Department of Defense network, Air Force network, or a local area network, while maintaining a high level of security and privacy.

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• 27.

### Which of the following is not a function that a virtual private network (VPN) concentrator performs?

• A.

Manages data transfer across the tunnel.

• B.

Encrypts and decrypts data.

• C.

Establishes tunnels.

• D.

Encapsulates data.

D. Encapsulates data.
Explanation
A virtual private network (VPN) concentrator performs various functions to ensure secure and efficient data transfer. It manages data transfer across the tunnel, encrypts and decrypts data, and establishes tunnels. However, encapsulating data is not a function of a VPN concentrator. Encapsulation is the process of adding headers and trailers to the data packet to ensure its secure transmission over the network. This task is typically performed by network devices such as routers and switches, rather than a VPN concentrator.

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• 28.

### What software do video compression circuits use to determine the amount of change that occurs between frames?

• A.

Pixel.

• B.

Buffer.

• C.

Keyframe.

• D.

Compression and decompression (codec) algorithm.

D. Compression and decompression (codec) algorithm.
Explanation
Video compression circuits use compression and decompression (codec) algorithms to determine the amount of change that occurs between frames. These algorithms analyze the video data and apply various techniques to reduce the size of the video file while maintaining acceptable quality. By comparing the frames and identifying the changes, the codec algorithm can efficiently encode and decode the video, resulting in compressed files that can be easily transmitted or stored.

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• 29.

### Simple network management protocol (SNMP) is a tool used by network administrators to manage network performance, investigate and solve network problems, and help plan for

• A.

Future growth.

• B.

Network security.

• C.

Remote monitoring.

• D.

Network contingencies.

A. Future growth.
Explanation
SNMP is a tool that allows network administrators to monitor and manage network performance, troubleshoot issues, and plan for the future. It provides information about network devices and their performance, allowing administrators to make informed decisions about network upgrades and expansions. Therefore, the correct answer is "future growth."

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• 30.

### Which of the following is not a basic SNMP command?

• A.

Write.

• B.

• C.

Trap.

• D.

Get.

D. Get.
Explanation
The SNMP (Simple Network Management Protocol) is used to manage and monitor network devices. The basic SNMP commands include Write, Read, and Trap. Write command is used to modify the configuration of a device, Read command is used to retrieve information from a device, and Trap command is used to send notifications to the SNMP manager. However, "Get" is not a basic SNMP command. "Get" is actually a subcommand of the Read command, used to retrieve specific information from a device.

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• 31.

### Which identity management process uses a fingerprint to authenticate a user?

• A.

Token.

• B.

Biometrics.

• C.

Multifactor.

• D.

Knowledge-based.

B. Biometrics.
Explanation
Biometrics is the correct answer because it refers to the identity management process that uses a fingerprint to authenticate a user. Biometrics involves the use of unique physical characteristics, such as fingerprints, iris patterns, or facial recognition, to verify a person's identity. By scanning and comparing the fingerprint, the system can ensure that the user is who they claim to be. This method is considered highly secure as it is difficult to replicate or fake someone's unique biometric traits.

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• 32.

### Which threat vector is considered more of an annoyance than an attack?

• A.

Virus.

• B.

Spam.

• C.

Spyware.

• D.

Phishing.

B. Spam.
Explanation
Spam is considered more of an annoyance than an attack because it involves the mass sending of unsolicited and irrelevant messages to a large number of recipients. While it can be disruptive and time-consuming to deal with, spam typically does not pose a direct threat to the security or integrity of a system or personal information. On the other hand, viruses, spyware, and phishing attacks are specifically designed to infiltrate and compromise systems, steal sensitive data, or deceive users into revealing confidential information, making them more dangerous and harmful.

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• 33.

### Which vulnerability preventive measure is a small piece of code that software developers create to address the flaws found in the original code of a program?

• A.

Patches.

• B.

Antivirus.

• C.

Software removal.

• D.

Vulnerability scanner.

A. Patches.
Explanation
Patches are a small piece of code that software developers create to address the flaws found in the original code of a program. They are used to fix vulnerabilities and improve the security of the software. Patches are typically released by the software vendor and need to be applied to the existing software installation to ensure that it is up to date and protected against known vulnerabilities. They are an important preventive measure to keep software secure and reduce the risk of exploitation by malicious actors.

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• 34.

### What physical security implementation will ensure continuous operation of critical network equipment?

• A.

Data encryption.

• B.

Virtual private network.

• C.

Uninterruptible power supply.

• D.

Network management system.

C. Uninterruptible power supply.
Explanation
An uninterruptible power supply (UPS) ensures continuous operation of critical network equipment by providing a backup power source in the event of a power outage or fluctuation. This helps prevent any disruption or damage to the equipment, allowing it to function seamlessly and ensuring the network remains operational. Data encryption, virtual private networks, and network management systems are important for securing the data and managing the network, but they do not directly address the issue of continuous operation in the event of a power failure.

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• 35.

### In general, you should deny direct dial-in access to a network device by disabling the

• A.

Console port.

• B.

Auxiliary port.

• C.

Interface ports.

• D.

Virtual terminal ports.

B. Auxiliary port.
Explanation
The correct answer is auxiliary port. In general, direct dial-in access to a network device should be denied, and this can be achieved by disabling the auxiliary port. The auxiliary port is typically used for out-of-band management purposes and allowing direct dial-in access through this port can pose a security risk. By disabling the auxiliary port, unauthorized access attempts can be prevented, enhancing the overall security of the network device.

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• Current Version
• Feb 22, 2024
Quiz Edited by
ProProfs Editorial Team
• May 14, 2017
Quiz Created by
Kevin

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