certmaster troubleshooting ethernet networks Flashcards
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
A
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.
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
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 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-related
C.Isolate subsystem variables
D.Test theory
B
Deciding whether the problem is hardware-related 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 that the transceiver is the source of the problem. What should the network operator perform?
A.Check patch cord termination
B.Use a loopback tool
C.Change the patch cord
D.Substitute known working hosts
B
The network operator can use a loopback tool to test for a bad port if the transceiver is the suspected issue. This will test connectivity between the transmitting and receiving capability of the physical 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
