CompTIA Network+ Exam N10-008 - Lesson 4: Troubleshooting Ethernet Networks

A help desk technician is trying to troubleshoot the end of a cable but is uncertain where the other end is. What could the technician use to help find the other end of the cable? A. Fox and Hound B. Multimeter C. Wire map tester D. Loopback tool

A. Fox and Hound A network tone generator and probe trace a cable from one end to the other. This device is also known as a Fox and Hound or a tone probe. A multimeter can check physical connectivity. The primary purpose of a multimeter is for testing electrical circuits, but it can test for the continuity of any sort of copper wire. A wire map tester is also available as a dedicated device. Wire map testers can identify continuity, shorts, and incorrect pins. If the problem is not the patch cords, then test the transceivers. The technician can use a loopback tool to test for a bad port.

A network technician is trying to troubleshoot attenuation and measure accordingly. What unit of measurement expresses attenuation? A. dB B. SNR C. ms D. Mbps

A. dB Attenuation is the loss of signal strength, measured in decibels (dB). dB expresses the ratio between two measurements, and in this case, signal strength at origin and destination. Noise is anything transmitted within or close to the channel that is not the intended signal and expressed as the signal-to-noise ratio (SNR). Important network performance characteristics are bandwidth, throughput, packet loss, and the speed at which the system delivers packets. Speed, measured as a unit of time, is typically milliseconds (ms). Throughput is an average data transfer rate achieved over a period of time, excluding encoding schemes, errors, and other losses incurred at the physical and data link layers. Its unit of measurement is in Mbps or Gbps.

A network technician is troubleshooting a connection from a client and decides to use the bottom to top troubleshooting methodology. Which step would the technician perform first? A. Determine subsystem B. Determine if hardware or software related C. Isolate subsystem variables D. Test theory

B. Determine if hardware or software related Deciding whether the problem is hardware or software-related (i.e., hardware) would be the first step. The physical layer (layer 1) is at the bottom of the OSI model. The next step would be to decide which hardware subsystem is affected. For example, the technician might troubleshoot the network interface card (NIC) or the cable. The technician may have to decide whether the problem is in the NIC adapter or connectors or the cabling (cabling), which would be an example of isolating subsystem variables. If, for example, the technician decides the issue is a cable and replaces it with a new cable, then that is an example of testing the theory.

A network operator is troubleshooting connectivity issues and suspects the transceiver. What should the network operator perform? A. Check patch cord termination B. Loopback tool C. Change the patch cord D. Substitute known working hosts

B. Loopback tool If the problem is not the patch cords, then test the transceivers. The network operator can use a loopback tool to test for a bad port. Assuming the network operator is investigating link failure (complete loss of connectivity), the first step is to check that the patch cords are properly terminated and connected to the network ports. If suspecting a fault, then the network operator would substitute the patch cord with a known good cable. If a loopback tool is unavailable, another approach is to substitute known working hosts by connecting a different computer to the link or swapping ports at the switch. This approach may have adverse impacts on the rest of the network.

A help desk technician is helping to troubleshoot connectivity issues. Users report that they are receiving a blinking amber light. This is indicative of what type of issue? A. Port disabled B. Disconnect at other end C. Fault detected D. Connected but no traffic

C. Fault detected A blinking amber light indicates that the system has detected a fault, such as a duplex mismatch or a spanning tree blocking. A solid amber light indicates that the port is disabled. On a switch, the network administrator probably has unused ports disabled and will need to enable them. No light indicates that the link is not working or disconnected at the other end. The user will most likely need to trace the cable to ensure the other end is plugged in where it is supposed to be. A solid green light indicates that the link is connected, but there is no traffic.

A systems manager is preplanning for the event that critical servers will fail. Which of the following would be the most likely plan of action? A. Repair B. Ignore C. Replace D. Destroy

C. Replace Replacing, while expensive, is expected for critical servers. Companies often have replacement parts and complete other servers on standby to take over for critical servers. Administrators will need to determine whether the cost of repair/time taken to reconfigure something makes this the best option. However, in the case of replacing critical services and actually having redundancy, repairing the system would be a better option. Not all problems are critical. If neither repair nor replacement is cost-effective, it may be best to either find a workaround or just document the issue and move on. If the systems manager decides to replace an old server, certain things, such as the hard drives, will most likely have to be destroyed.

A help desk operator is troubleshooting a site that is no longer responsive. Which of the following is the last step the operator should perform? A. Implement solution B. Determine cause C. Establish plan of action D. Document findings

D. Document findings While the last step in troubleshooting is to document findings, the last step presented in this scenario is to verify full system functionality as documenting is not an available response. Implement the solution or escalate as necessary occurs before verification. The technician has to apply the solution first, or there would not be much point in verifying. Testing the theory to determine the cause occurs after establishing the theory. Once confirming the theory, determine the next steps to resolve the problem. If the theory is not confirmed, then re-establish a new theory or escalate. After determining the cause, the operator should establish a plan of action to resolve the problem and identify potential effects.

A help desk operator is troubleshooting a site that is no longer responsive. Which of the following is the first step the operator should perform? A. Determine cause B. Establish plan of action C. Document findings D. Establish a theory of probable cause

D. Establish a theory of probable cause Establish a theory of probable cause that includes, but not limited to, questioning the obvious, considering multiple approaches, the top to bottom/bottom to top OSI model, and divide and conquer. Test the theory to determine the cause after establishing a theory. Once the theory is confirmed, determine the next steps to resolve the problem. If the theory is not confirmed, then re-establish a new theory or escalate. After determining the cause, the operator should establish a plan of action to resolve the problem and identify potential effects. Document findings, actions, and outcomes are normally a continuous part of the process, but in the end, the operator needs to ensure documentation of all applicable information.

A network operator is trying to troubleshoot kinks and imperfections in cabling that could affect performance. What should the network operator use to test the cabling? A. dB B. SNR C. ms D. TDR

D. TDR A cable tester might incorporate the function of a time domain reflectometer (TDR). A TDR measures the length of a cable run and locates kinks and other imperfections in cables that could affect performance. Attenuation is the loss of signal strength, expressed in decibels (dB). dB measures the ratio between two measurements, such as signal strength at origin and destination. Noise is anything transmitted within or close to the channel that is not the intended signal and expressed as the signal-to-noise ratio (SNR). Important network performance characteristics are bandwidth, throughput, packet loss, and the speed at which the system delivers packets. Speed, measured as a unit of time, is typically milliseconds (ms).

A help desk technician is troubleshooting communications between a client and print server. They are trying to perform the step to identify symptoms and duplicate the problem. Which of the following does NOT fall under this step? A. Question the obvious B. Physical inspection C. Check system logs D. Use a test system

Questioning the obvious falls under establishing a theory of probable cause. This step includes making a physical inspection and looking for something out of the ordinary. Sometimes the issue can be a layer 1 issue. This step also includes checking system logs or diagnostic software for information. This can often be helpful in troubleshooting, although it does not always indicate the root of the problem. Technicians should duplicate the problem on the user's system or a test system. They will need to try to follow the same steps as the user.