Exam N10-008 topic 1 question 309 discussion

Very obviously, C. Mike Meyers "CRC Errors CRC errors in this section is a duplicate in the objectives, and appears in the previous section.They occur when packets contain invalid values, and possible causes include a faulty port, poor wiring, and even electromagnetic interference (EMI)." Emmett Dulaney "EMI is a problem when cables are installed near electrical devices, such as air conditioners or fluorescent light fixtures. If a network medium is placed close enough to such a device, the signal within the cable might become corrupt. Network media vary in their resistance to the effects of EMI. Standard unshielded twisted-pair (UTP) cable is susceptible to EMI, whereas fiber cable, with its light transmissions, is resistant to EMI. When deciding on a particular medium, consider where it will run and the impact EMI can have on the installation."

How do they get the answers for these questions? I've seen several questions like this one where over 90% of the people end up voting for the wrong answer and there is never an official explanation as why the correct answer is the right one.

Only real option is C

Remember, whenever you see CRC's, think of Layer 1 stuff: Cabling in this instance!

it's USP - unshielded.... over flourescent lights... interference.

correct answer is C because there is interference

c is the correct one

The most likely cause of the CRC errors in this scenario is the use of UTP cabling in the ceiling above the fluorescent lights. UTP cabling is susceptible to interference from electrical sources, such as fluorescent lights, which can cause errors in data transmission. This interference can result in CRC errors, which occur when the cyclic redundancy check (CRC) detects that the data sent does not match the data received. Therefore, the UTP cabling should be replaced with shielded cabling to reduce the interference and eliminate the CRC errors.

C. Electromagnetic interference is the MOST likely cause of the CRC errors. The installation of the new cable uplinks in close proximity to the fluorescent lights can result in high levels of electromagnetic interference that cause the UTP cabling to transmit incorrect data, leading to an increase in CRC errors.

The answer is C because Electromagnetic Interference (EMI) is caused by the presence of electrical and electronic devices that emit electromagnetic waves, such as fluorescent lights. These waves can interfere with the signals in the UTP cabling, causing errors such as CRC errors. When the WAPs were reconnected after the remodeling, the presence of the new fluorescent lights, which were installed in the ceiling above the office area, likely caused the EMI and subsequent CRC errors.

Question states fluorescent lights and Unshielded Twisted Pair (UTP). It's clearly C.

The most likely cause of the CRC errors in this scenario is B, PoE and UTP incompatibility. CRC, or Cyclic Redundancy Check, is an error detection mechanism used in data transmission to ensure the integrity of the data being transmitted. When a CRC error is detected, it indicates that there is a problem with the data being transmitted, such as corruption or loss of information.

Fluorescent lights are the key here.

The question already states that the cable is near fluorescent lights and it is UNSHIELDED twisted pair, therefore it has to be C.

Electromagnetic interference is the correct answer here!!