Exam 200-301 topic 1 question 1093 discussion

I think the answer should be: single mode - long distance - DWDM -> "WDM and DWDM use single-mode fiber to carry multiple lightwaves of differing frequencies.", see link https://www.cisco.com/c/dam/global/de_at/assets/docs/dwdm.pdf multimode - single wavelength - core diameter 62.5 or 50 microns -> "Typical cores sizes are 50 microns and 62.5 microns and a typical operating wavelength for multi-mode fiber is 850nm.", see link https://blogs.cisco.com/sp/fiberopticspt2singlemultifiber -> "Most of Cisco’s multimode transceivers are single-wavelength devices operating at 850 nm", see link https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/diff-om4-om5-multimode-fiber-wp.html

This question was incorrectly input, there are 3 choices that match single mode fiber as is apparent from earlier questions, the only choice that is multimode is Core Diameter, the rest are single mode, you won't get this question on the exam with these choices so just skip

given answers are correct but i think that the answer "typically used for DWDM optical systems spanning long distances" is not correct for mutimode. Multimode fiber can be used in certain DWDM (Dense Wavelength Division Multiplexing) applications but NOT FOR ONG DISTANCE. While single-mode fiber has been the preferred choice for DWDM systems, multimode fiber can be used in certain DWDM applications, particularly those with shorter transmission distances. So i think this answer in a mistake from the website. https://www.genuinemodules.com/is-dwdm-single-mode-or-multimode_a1958#:~:text=Multimode%20fiber%20can%20be%20used%20in%20certain%20DWDM%20(Dense%20Wavelength,implemented%20using%20single%2Dmode%20fiber.

I think by single wavelength it means we only use one range of wavelength for single-mode fiber, not when using DWDM where we multiplex multiple wavelength together. There are three main wavelengths used for fiber optics—850 nm and 1300 nm for multi-mode and 1550 nm for single-mode (1310 nm is also a single-mode wavelength, but is less popular). https://www.garlandtechnology.com/blog/fiber-facts-yes-you-do-need-to-read-this So the answer I would choose is: single-mode: single wavelength, dwdm multimode: longer distance(compared to copper), core diameter 62.5(OM1,Fddi), 50 (others)

Correct https://www.ciena.com/insights/what-is/What-Is-WDM.html

Single mode: DWDM, Single wavelength, and long distance. Multimode: Core diameter between 60 and 62.5. I can't say if the question is incorrect, but in the exam, I would drop DWDM under multimode if I had no other choices.

I think we should switch answers "Use a single wavelength on light" and "is used for DWDM"