Common Network Issues and Solutions

A department is reporting network issues.

Users can ping each other and the switch, but not the default gateway.

When looking at a wiring diagram and a physical blueprint, a technician notices the 1000BaseLX SFP connects to a distribution switch via a cable that runs behind a large industrial refrigerator.

The technician also notices both switches have been worked on recently.

Which of the following is MOST likely the issue?

A.

EMI

B.

TX/RX reverse

C.

Open/short

D.

Attenuation.

A.

Based on the symptoms and the information provided, the most likely issue is electromagnetic interference (EMI) causing signal degradation and preventing communication with the default gateway.

Firstly, users being able to ping each other and the switch but not the default gateway suggests that there is an issue with the connectivity between the department's network and the rest of the network. Since the switch can be pinged, it is unlikely to be a switch port issue. Therefore, it is most likely a problem with the connection between the switch and the default gateway.

Secondly, the fact that the cable connecting the 1000BaseLX SFP to the distribution switch runs behind a large industrial refrigerator suggests that it may be subject to EMI. Electromagnetic interference can be caused by various sources, such as fluorescent lights, motors, or refrigerators, and can cause signal distortion, loss, or noise on network cabling.

Finally, the fact that both switches have been worked on recently could also be a contributing factor. It is possible that during the maintenance work, the cabling was moved or disturbed, which could have caused additional EMI or damaged the cable itself.

Therefore, based on the symptoms and the information provided, EMI is the most likely issue causing the network problem. The solution would involve re-routing the cable away from the source of interference or shielding it, or replacing the cable altogether with a better-shielded one.