100-150 Question 111
Select 2A small office network is experiencing intermittent connectivity issues during business hours. The environment includes Cat5e Ethernet cables, a fiber-optic connection to the ISP, and a Wi-Fi network using the 802.11ac standard. Upon investigation, you discover that the Ethernet cables run parallel to power lines, the fiber connection is working properly, and the Wi-Fi network is located near a microwave oven in the break room. What are the two most likely causes of the connectivity issues?
- A
Electromagnetic interference (EMI) from the power lines affecting the Ethernet cables
- B
Signal degradation in the fiber-optic connection to the ISP
- C
Radio frequency interference (RFI) from the microwave oven affecting the Wi-Fi network
- D
The Wi-Fi network is using an outdated 802.11 standard
- E
Physical damage to the Ethernet cables
Show answer and explanation
Correct answers: A, C
Explanation
The two most likely causes of the connectivity issues are electromagnetic interference (EMI) from the power lines affecting the copper Ethernet cables and radio frequency interference (RFI) from the microwave oven affecting the Wi-Fi network. Copper cables like Cat5e are vulnerable to EMI when placed near power sources, and Wi-Fi signals in the 2.4 GHz band can be disrupted by devices like microwave ovens. These environmental factors align with the described symptoms of intermittent connectivity.
- A. Correct.
Copper cables, such as Cat5e, are susceptible to electromagnetic interference (EMI) when installed too close to power lines, which can cause intermittent connectivity issues.
- B. Incorrect.
Fiber-optic cables are immune to electromagnetic interference and typically do not experience signal degradation unless physically damaged or improperly terminated. Since the fiber connection is confirmed to be working properly, this is unlikely the cause.
- C. Correct.
Microwave ovens operate in the 2.4 GHz spectrum, which overlaps with some Wi-Fi frequencies, potentially causing radio frequency interference (RFI) and disrupting wireless connectivity.
- D. Incorrect.
The 802.11ac standard is modern and capable of high performance. There is no indication that the Wi-Fi standard is outdated or causing issues in this scenario.
- E. Incorrect.
Physical damage to Ethernet cables could cause connectivity problems, but there is no evidence of damage in this case. The scenario specifically highlights interference from power lines as a potential issue.