5.2 troubleshoot common cable connectivity issues and select the appropriate tools.

Question 1

Throughput

Answer 1

Throughput refers to the amount of data successfully transferred from one point to another within a specific period, typically measured in bits per second (bps). It is a practical measure of a network’s performance, indicating how much data is actually transmitted compared to the theoretical maximum bandwidth.

For the exam, understand that throughput can be affected by factors like network congestion, packet loss, and latency. It is a key metric for determining network efficiency and identifying performance bottlenecks.

Question 2

Speed

Answer 2

Speed in networking refers to the rate at which data can be transmitted over a network link, typically measured in bits per second (bps). This can include both the upload and download speeds, reflecting how fast data moves between devices on a network.

For the exam, you should understand that while speed indicates the capacity of a connection, it doesn’t always reflect actual performance due to factors like latency, interference, and congestion. Differentiating between bandwidth (the maximum possible speed) and throughput (actual speed) is also important.

Question 3

Distance

Answer 3

Distance in networking refers to the physical or logical space between network devices, affecting how data is transmitted. As the distance between devices increases, signal degradation or latency can occur, especially in wired and wireless networks. Technologies like fiber optics, copper cables, and wireless signals have different effective ranges.

For the exam, understand how distance impacts network design, such as using repeaters or signal boosters to extend ranges, and the limits of various transmission media like copper (shorter distances) versus fiber optic cables (longer distances with less degradation).

Question 4

• Shielded and unshielded

Answer 4

Shielded and unshielded refer to types of cabling used in networking that protect against electromagnetic interference (EMI). Shielded cables have an additional layer of insulation, typically made from materials like foil or braided wire, which helps reduce interference from external sources. This makes them suitable for environments with high EMI, such as industrial settings. Unshielded cables, on the other hand, lack this protective layer, making them less expensive and easier to install, but more susceptible to interference.

For the exam, be familiar with the differences in applications for shielded versus unshielded cables, such as using shielded twisted pair (STP) in sensitive environments and unshielded twisted pair (UTP) in standard office settings. Understand the implications of using each type regarding performance, cost, and installation.

Question 5

Plenum and riser-rated

Answer 5

Plenum-rated and riser-rated cables are classifications based on the types of environments in which they can be safely installed. Plenum-rated cables are designed for spaces with air circulation for heating and air conditioning, like ceiling spaces. They have a low-smoke and fire-resistant jacket, making them safer in the event of a fire, as they emit less toxic smoke and reduce flame spread. Riser-rated cables, while also fire-resistant, are intended for vertical spaces between floors, such as conduits or elevator shafts. They do not have the same level of protection as plenum-rated cables but are still designed to limit flame spread between floors.

For your exam, understand the specific applications for both types of cables. Recognize that the choice between plenum and riser-rated cables affects safety standards in building wiring and may have implications for building codes. Be prepared to identify scenarios where each type would be appropriate based on the environment’s needs.

Question 6

Rollover cable/console cable

Answer 6

A rollover cable, also known as a console cable, is a type of serial cable used to connect a computer or terminal to the console port of a network device, such as a router or switch. This cable features an RJ-45 connector on both ends, but its wiring is reversed, meaning pin one on one end connects to pin eight on the other, creating a “rollover” effect. This unique wiring allows for direct console access to the device for configuration and management.

For the exam, it is important to know the primary use of a rollover cable in network management and troubleshooting. Familiarize yourself with the physical characteristics of the cable, such as its RJ-45 connectors and the specific pin configuration. Understanding scenarios where you would need to use a rollover cable, such as initial device setup or recovery from misconfigurations, can also be beneficial.

Question 7

Crossover cable

Answer 7

A crossover cable is a type of Ethernet cable designed to connect two similar devices directly, such as two computers, switches, or routers, without the need for a hub or switch. Unlike standard straight-through cables, a crossover cable has its wiring configured in such a way that the send and receive pairs are crossed over, allowing for the proper transmission of data between the two devices.

For the exam, it’s essential to recognize the specific scenarios in which a crossover cable is utilized, such as connecting two computers for file sharing or linking switches together. Familiarity with the physical appearance of the cable, including the RJ-45 connectors and wiring patterns, is also important. Be aware that many modern devices can automatically detect and adjust to the type of connection needed, making crossover cables less common than in the past.

Question 8

Power over Ethernet

Answer 8

Power over Ethernet (PoE) is a technology that allows network cables to carry electrical power along with data to powered devices such as IP cameras, VoIP phones, and wireless access points. This eliminates the need for additional power sources, making installations simpler and more flexible. PoE works by using the spare pairs of wires in standard Ethernet cables to deliver power while transmitting data over the same cable.

For the exam, you should understand the different PoE standards, including IEEE 802.3af (provides up to 15.4 watts), IEEE 802.3at (also known as PoE+, provides up to 30 watts), and IEEE 802.3bt (also known as PoE++, provides up to 60 or 100 watts). It’s important to know the benefits of PoE, such as reduced installation costs and enhanced device mobility. Additionally, be familiar with the components involved in PoE systems, including PoE switches, injectors, and powered devices.

Question 9

Attenuation

Answer 9

Attenuation refers to the reduction in strength or intensity of a signal as it travels through a transmission medium, such as copper or fiber optic cables. This degradation can occur due to various factors, including distance, interference, and the physical properties of the medium. In networking, attenuation is a crucial consideration because it can lead to data loss or poor signal quality, affecting overall network performance.

For the exam, you should know how attenuation is measured, typically in decibels (dB), and understand the acceptable levels of attenuation for different types of cabling, such as twisted-pair, coaxial, and fiber optic cables. Familiarity with ways to mitigate attenuation, such as using repeaters, amplifiers, or selecting higher-quality cables, is also important. Understanding the relationship between distance and attenuation will help you evaluate network design and performance.

Question 10

Interference

Answer 10

Interference refers to the disruption or degradation of a signal as it travels through a transmission medium, caused by the presence of other signals or external factors. In networking, interference can originate from various sources, such as electromagnetic interference (EMI) from electrical devices, radio frequency interference (RFI) from wireless signals, or crosstalk between adjacent cables. These disturbances can lead to data corruption, reduced network performance, and increased latency.

For the exam, it’s essential to recognize different types of interference and their potential impacts on network operations. You should be familiar with techniques to mitigate interference, such as using shielded cables, implementing proper cable management, and choosing appropriate frequencies for wireless communication. Understanding the concept of signal-to-noise ratio (SNR) is also important, as it helps gauge the quality of a signal in the presence of interference.

Question 11

• Decibel (dB) loss

Answer 11

Decibel (dB) loss refers to the measurement of signal attenuation as it travels through a medium, often expressed in decibels. It quantifies the reduction in power or strength of a signal as it moves through cables, connectors, or other components in a network. A higher dB loss indicates more significant signal degradation, which can affect the overall performance and reliability of the network. In fiber optic communication, for instance, the dB loss is crucial for determining the maximum distance a signal can travel without becoming unusable.

For the exam, it’s important to understand how to calculate dB loss and the implications it has on network design. You should be familiar with the acceptable dB loss limits for different types of cables, as excessive loss can lead to connectivity issues and reduced data transmission rates. Knowing how to measure and interpret dB loss helps in troubleshooting and optimizing network performance.

Question 12

• Incorrect pinout

Answer 12

Incorrect pinout refers to the misconfiguration of the wiring arrangement in network cables, particularly in twisted pair cables such as Ethernet. Each pin in the connector is designated for a specific function, and when the wires are connected to the wrong pins, it can lead to connectivity issues or complete failure of the connection. For example, in a standard RJ-45 connector used for Ethernet, specific pins are assigned for transmitting and receiving data. If these pins are incorrectly wired, data transmission will not occur correctly.

For the exam, it’s essential to understand the significance of correct pinout configurations in networking cables. You should be able to identify common wiring standards, such as T568A and T568B, and know how to verify and correct pinouts when troubleshooting connection problems. Recognizing the impact of incorrect pinouts on network performance is crucial for effective cable management and ensuring reliable communication between devices.

Question 13

• Bad ports

Answer 13

Bad ports refer to physical connection points on network devices, such as switches or routers, that have become non-functional due to various reasons. These ports may fail to establish a connection or transmit data correctly, leading to network interruptions or degraded performance for devices connected to them. Common causes of bad ports include hardware failure, electrical issues, or damage from physical stress or environmental factors.

For the exam, it’s important to recognize the symptoms of bad ports, such as inability to connect devices, intermittent connectivity, or performance issues on the network segment. You should understand troubleshooting steps, including testing different devices on the port, replacing cables, and using diagnostic tools to isolate the issue. Familiarity with checking the status of ports through management interfaces or logs can also be beneficial in identifying and resolving port-related problems effectively.

Question 14

• Open/short

Answer 14

An open or short circuit refers to a condition in electrical wiring where the expected continuity is disrupted. An open circuit occurs when there is a break in the electrical path, preventing current from flowing. This can happen due to a disconnected wire, a broken cable, or faulty connectors. In contrast, a short circuit occurs when there is an unintended connection between two points in a circuit, allowing current to bypass the intended path. This can result in excessive current flow, potentially damaging equipment or causing safety hazards.

For the exam, you should be able to identify the symptoms of open and short circuits, such as loss of connectivity or unusual behavior in devices. Understanding how to use testing tools like multimeters to check for continuity in a cable is essential. You should also know the troubleshooting steps, including visual inspections, cable testing, and isolating sections of the circuit to pinpoint the fault. Familiarity with how these issues can affect network performance and reliability will also be helpful.

Question 15

Light-emitting diode (LED) status indicators

Answer 15

Light-emitting diode (LED) status indicators are small lights used in networking equipment and devices to convey the operational status of the device. These indicators can show various conditions, such as power on/off, network connectivity, data transmission activity, and error states. The color and behavior of the LED often provide specific information; for example, a solid green light might indicate normal operation, while a flashing red light could signal a problem or error.

For the exam, it’s important to understand the common meanings of different LED statuses on devices like routers, switches, and network interfaces. You should be familiar with interpreting these signals for troubleshooting purposes. Knowing how to use LED indicators to quickly diagnose issues can be crucial in maintaining network reliability. Familiarity with the documentation for specific devices to understand their LED status indicators is also beneficial.

Question 16

Incorrect transceivers

Answer 16

Incorrect transceivers refer to instances when the wrong type of transceiver module is used in a networking device, such as a switch or router. Transceivers are essential components that facilitate the transmission and reception of data over a network. They convert electrical signals to optical signals and vice versa. Each networking environment requires specific types of transceivers that match the network’s speed, distance, and medium, such as fiber or copper.

For the exam, you should be aware of the different types of transceivers, such as SFP, SFP+, QSFP, and others, and their specifications. Understanding the consequences of using incorrect transceivers, such as reduced performance, incompatibility issues, or complete communication failure, is crucial. Additionally, recognizing the importance of matching transceiver types with the corresponding network equipment will help in effective troubleshooting and network design.

Question 17

• Duplexing issues

Answer 17

Duplexing issues occur when there is a mismatch between the duplex settings of network devices, which can lead to communication problems. Duplex refers to the ability of a network device to send and receive data simultaneously (full duplex) or one at a time (half duplex). Full duplex allows for smoother communication and higher throughput, while half duplex may cause collisions if both devices attempt to send data simultaneously.

For the exam, you should understand the differences between full duplex and half duplex, including their advantages and disadvantages. You may encounter scenarios where duplex mismatches lead to poor network performance, such as slow speeds or dropped connections. Familiarity with how to configure and troubleshoot duplex settings on switches, routers, and network interface cards (NICs) is important for maintaining optimal network functionality.

Question 18

• Transmit and receive (TX/RX) reversed

Answer 18

Transmit and receive (TX/RX) reversed refers to a misconfiguration in network cabling where the transmit and receive pins on a cable are incorrectly connected. This issue typically arises when creating or connecting Ethernet cables, resulting in devices being unable to communicate effectively. For example, in a standard Ethernet cable, the transmit pins on one end should connect to the receive pins on the other end. If this is reversed, data sent from one device cannot be properly received by the other.

For your exam, it’s important to recognize the symptoms of this problem, such as one-way communication or failure to establish a network connection. Understanding how to identify and correct TX/RX reversal, including checking cable pinouts and ensuring proper cabling standards, is crucial for troubleshooting network issues. Familiarity with tools like cable testers can also aid in detecting these misconfigurations.

Question 19

• Dirty optical cables

Answer 19

Dirty optical cables refer to fiber optic cables that have accumulated dust, debris, or smudges on the connector ends, which can significantly affect signal transmission. Fiber optic cables transmit data using light, and any obstruction or impurities on the optical surface can cause signal loss, reduced performance, and increased attenuation. This issue is particularly critical in high-speed networks where maintaining optimal signal clarity is essential.

For your exam, you should be aware of the symptoms of dirty optical cables, such as intermittent connectivity, slow data transfer rates, and increased error rates. Understanding proper maintenance practices, such as regular cleaning of fiber optic connectors with appropriate tools and solutions, is key to preventing this problem. You should also know that using fiber optic cleaning kits and adhering to manufacturer guidelines can help ensure the longevity and performance of optical cables.

Question 20

Cable crimper

Answer 20

A cable crimper is a hand tool used for terminating and connecting various types of cables, most commonly for network and telecommunications applications. This tool allows users to attach connectors, such as RJ-45 or RJ-11 connectors, to the ends of twisted pair or coaxial cables. Crimping involves inserting the connector onto the stripped end of the cable and then using the crimper to compress the connector onto the cable, creating a secure and reliable electrical connection.

For your exam, it’s important to understand the crimping process and know the difference between various connectors used with specific cable types. Familiarity with different cable types, such as Ethernet (Cat5e, Cat6) and phone lines, is essential. Additionally, you should recognize the significance of using the correct tool for the job, as improper crimping can lead to connectivity issues and network problems. Knowledge of how to troubleshoot crimping issues, like loose connections or improper pinouts, can also be beneficial.

Question 21

Punchdown tool

Answer 21

A punchdown tool is a specialized hand tool used for connecting and terminating network cables, particularly in structured cabling environments. It is primarily used to insert wire pairs into the slots of a punchdown block or patch panel, ensuring a secure connection between the cable and the equipment. The tool typically features a blade that punches the wire down into the terminal while cutting off any excess wire, which helps maintain a neat and organized setup.

For the exam, you should know how to use a punchdown tool correctly, including the importance of following color codes for wiring. Understanding the differences between various types of punchdown tools, such as those with adjustable blades or interchangeable tips, can be useful. Additionally, be familiar with common issues that can arise from improper use, like loose connections or crosstalk, and how to troubleshoot them. Recognizing the tool’s role in maintaining network performance and reliability is also important.

Question 22

• Tone generator

Answer 22

A tone generator is a diagnostic tool used in networking and telecommunications to send a specific audio frequency signal through a cable. This signal can then be traced using a tone probe, allowing technicians to identify and locate cables quickly and accurately within walls, ceilings, or conduits. The tone generator works by applying a tone to the wire, which can be picked up by the probe, helping to determine the cable’s path and verify connections.

For the exam, you should understand the basic operation of a tone generator and how it is used in conjunction with a tone probe. Familiarize yourself with its application in troubleshooting network issues, such as identifying cable faults or verifying proper connections in structured cabling systems. Knowing the differences between continuous tone and pulsed tone modes, and when to use each can also be beneficial. Recognizing the importance of this tool in maintaining network integrity and efficiency will be essential for practical scenarios in the field.

Question 23

• Loopback adapter

Answer 23

A loopback adapter is a hardware device used in networking to test and troubleshoot network interfaces. It works by connecting the transmit (TX) and receive (RX) pins of a network interface card (NIC) together, effectively creating a loopback circuit. This allows data sent from the NIC to be immediately received back by the same interface, enabling technicians to verify that the network hardware is functioning correctly.

For the exam, it’s important to know that loopback adapters are commonly used during testing phases to diagnose issues with network connections and configurations. Understanding how to use a loopback adapter for tasks like checking the status of a NIC or validating network configurations can help you identify problems before they escalate. You should also be aware of different types of loopback tests, such as software loopback tests, and their significance in troubleshooting scenarios.

Question 24

• Optical time-domain Reflectometer (OTDR)

Answer 24

An Optical Time-Domain Reflectometer (OTDR) is a testing device used to analyze optical fibers by sending pulses of light into the fiber and measuring the light that is reflected back. This tool provides valuable information about the condition of the fiber, including its length, attenuation (loss of signal strength), and the location of faults or splices along the cable. By interpreting the reflections, technicians can create a detailed profile of the fiber’s performance and identify any issues affecting its transmission capabilities.

For the exam, it’s essential to understand that OTDRs are critical for maintaining and troubleshooting fiber optic networks. You should be familiar with how OTDRs operate, the type of data they provide, and how that information is utilized in diagnosing fiber optic issues. Recognizing the importance of OTDRs in ensuring optimal fiber performance and the steps involved in conducting a proper OTDR test may also be beneficial.

Question 25

Multimeter

Answer 25

A multimeter is a versatile electronic measuring instrument used to measure voltage, current, and resistance in electrical circuits. It can be configured to operate in different modes, allowing it to serve various functions such as measuring direct current (DC) and alternating current (AC) voltages, checking continuity, and assessing the resistance of components. Multimeters can be either digital or analog, with digital multimeters (DMMs) being more common due to their ease of reading and accuracy.

For the exam, it’s important to know how to properly use a multimeter for testing electrical circuits, including the correct settings for voltage, current, and resistance measurements. You should be familiar with the safety precautions when using a multimeter, such as ensuring the device is properly calibrated and knowing how to measure different electrical values without causing damage to the circuit or the multimeter itself. Understanding the significance of multimeters in troubleshooting network devices and electrical systems will also be crucial.

Question 26

• Cable tester

Answer 26

A cable tester is a device used to verify the integrity and performance of cables, particularly network cables like Ethernet, coaxial, and telephone lines. It checks for issues such as continuity, miswiring, shorts, and open circuits, ensuring that the cable can reliably transmit data. Cable testers typically come in two main types: basic testers that only check continuity and more advanced testers that can measure parameters like signal loss, capacitance, and resistance.

For the exam, it’s important to understand the different types of cable testers and their specific functions. You should know how to use a cable tester to troubleshoot issues in cabling, including interpreting the results it provides. Familiarity with common cabling standards, such as T568A and T568B wiring schemes, will also help in understanding the significance of proper wiring and the role of a cable tester in maintaining network reliability.

Question 27

• Wire map

Answer 27

A wire map is a diagnostic feature found in cable testers that shows the connectivity of individual wires within a cable. It indicates how the wires are terminated at each end and whether they are correctly wired according to standards such as T568A or T568B. A proper wire map will confirm that all pairs are connected in the correct sequence, with no shorts, opens, or crossed connections.

For the exam, it’s crucial to understand the significance of a wire map in troubleshooting cabling issues. You should be able to recognize common wiring problems, such as reversed pairs or miswiring, which can lead to network performance issues. Knowing how to interpret the wire map results will help you identify specific faults in the cabling system, allowing for more effective troubleshooting and repair.

Question 28

Tap

Answer 28

A tap, in networking and telecommunications, refers to a device that allows for the interception of data from a network cable. This device is often used in monitoring and diagnostic setups to capture network traffic for analysis without disrupting the actual data flow. Taps can be passive or active, with passive taps simply allowing data to pass through while mirroring the traffic to another device, and active taps amplifying the signal for better transmission.

For the exam, it’s important to know the function and types of taps. You may need to understand how they differ from other monitoring tools like packet sniffers and the implications of using taps for network security and performance analysis. Additionally, be aware of potential privacy and legal considerations when intercepting network traffic.

Question 29

• Fusion splicers

Answer 29

A fusion splicer is a device used to join two optical fibers together by melting their ends, creating a strong and low-loss connection. The process involves aligning the fibers with precision, applying heat to fuse them, and typically results in minimal signal loss compared to other methods, such as mechanical splicing. Fusion splicing is commonly used in telecommunications to connect fiber optic cables for high-speed data transmission.

For the exam, it’s essential to understand how a fusion splicer operates and the benefits it provides in fiber optic installations. You may be asked about the advantages of fusion splicing over other splicing methods, such as its durability and lower insertion loss. Additionally, familiarity with the maintenance and care of fusion splicers can be helpful, as proper handling can ensure long-lasting performance and reliable connections.

Question 30

• Spectrum analyzers

Answer 30

A spectrum analyzer is a device used to measure the magnitude of an input signal versus frequency within a specified frequency range. It provides a visual representation of the signal’s amplitude across different frequencies, allowing for the analysis of various characteristics, such as bandwidth, frequency components, and signal distortion. Spectrum analyzers are essential in diagnosing issues related to electromagnetic interference, signal quality, and network performance in both wired and wireless environments.

For the exam, it’s important to know the basic functions of a spectrum analyzer, such as identifying frequencies, measuring signal strength, and detecting unwanted signals or interference. Understanding how to interpret the graphical output of a spectrum analyzer, which typically displays amplitude on the vertical axis and frequency on the horizontal axis, is crucial. You may also encounter questions about the application of spectrum analyzers in troubleshooting wireless networks and optimizing performance by analyzing the radio frequency spectrum.

Question 31

• Snips/cutters

Answer 31

Snips, also known as wire cutters or cable cutters, are hand tools designed for cutting various types of wire, cable, and other materials. They come in different sizes and designs, each suited for specific tasks. For instance, wire snips are typically used for cutting through smaller gauge wires, while larger cable cutters can handle thicker cables used in networking or electrical applications. The blades of snips are often designed for precision, allowing for clean cuts without fraying or damaging the material.

For the exam, it’s essential to understand the different types of snips and cutters, including their specific uses in network cabling and installation. You should be familiar with the importance of using the appropriate tool for the job to ensure safety and maintain the integrity of the cables being worked on. Additionally, knowing basic maintenance practices, such as keeping the blades clean and properly adjusted, can help in prolonging the lifespan of the tool and ensuring efficient operation during installation or repair tasks.

Question 32

• Cable stripper

Answer 32

A cable stripper is a specialized tool designed to remove the insulation from electrical cables and wires without damaging the underlying conductors. It typically features adjustable blades or cutting edges that allow users to select the appropriate depth for different wire gauges. By stripping the insulation, technicians can prepare wires for connections, whether for networking, electrical installations, or other applications.

For the exam, it’s important to know how a cable stripper functions and the different types available, such as manual strippers and automatic strippers. Understanding when and how to use a cable stripper correctly is crucial, as improper use can lead to damaged conductors, which can affect connectivity and signal quality. Familiarity with safety precautions while using this tool is also essential, as working with live wires can pose risks.

Question 33

• Fiber light meter

Answer 33

A fiber light meter is a testing device used to measure the amount of light transmitted through fiber optic cables. It helps technicians assess the quality and integrity of fiber installations by determining the optical power levels at different points along the fiber. By connecting the light meter to a fiber optic cable, users can obtain readings that indicate the strength of the signal being transmitted, which can help identify issues such as excessive attenuation, bends, or faulty connectors.

For the exam, it’s essential to understand the purpose of a fiber light meter in troubleshooting and maintaining fiber optic networks. You should be familiar with how to operate the device, interpret its readings, and recognize the acceptable power levels for different types of fiber. Additionally, knowing the implications of low readings, such as potential fiber damage or connection problems, is crucial for network diagnostics and ensuring optimal performance.