Exam 300-425 topic 1 question 144 discussion

20 mW (≈13 dBm) falls within the generally recommended “15–20 mW” range for predictive/location-ready designs, so conceptually it isn’t wildly off. However: Cisco’s best-practice guidance (and the exam’s “gold-standard” call-out) is 18 mW, because that’s closest to matching a typical client’s transmit power (~15 dBm) without overshooting and enlarging your cell radius. Rounding up to 20 mW (choice C) would work in most real-world surveys, but it gives you slightly larger overlap cells—so the exam deems 18 mW (choice B) the “more accurate” answer. In short: C isn’t strictly wrong in practice, but B is the precise, exam-correct figure.

For predictive-design site planning with location readiness (i.e. fingerprinting) and to keep cell sizes small (mitigating co-channel interference), Cisco recommends using an AP transmit power that roughly matches a client’s transmit power—18 mW. At that level you get: Good overlap between adjacent AP cells for accurate location fingerprint collection Limited cell radius, which keeps co-channel interference down in dense deployments The other options don’t strike that balance: 10 mW (A) is generally too low to guarantee reliable coverage for fingerprinting. 20 mW (C) is close, but the published best practice calls out 18 mW specifically. 50 mW (D) produces overly large cells, increasing adjacency overlap and interference.

The correct answer is: A. 10 mW For location readiness and interference mitigation, the recommended power level is typically 10 mW because: It provides a more consistent and accurate representation of client device power levels, which are usually lower than AP maximum output. Using 10 mW reduces the risk of excessive cell overlap and co-channel interference, leading to better location accuracy. It ensures a balanced coverage area, essential for accurate location tracking and minimal interference.

When you check the signal coverage, verify that the AP radio transmit power does not use a transmit power greater than what the client devices can support. For example, by default, the Cisco Unified Wireless IP Phone 7925G uses the highest available transmit power by default (17 dBm / 50 mW for 2.4 GHz and 16 dBm / 40 mW for 5 GHz). https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-wireless-controllers/116057-site-survey-guidelines-wlan-00.html

Read this Chapter 5. Applying Wireless Design Requirements As you perform a survey, try to keep the AP power reduced to half that of the maximum transmit power you expect to find in any client. This will provide a margin or buffer that you can leverage if you need to adjust any AP transmit power levels, while staying within the capabilities of most client devices. the recommendation is to keep the AP power reduced to half of the maximum transmit power expected for client devices. This approach helps in providing flexibility for power adjustments and avoids interference, while ensuring compatibility with most client devices. Assuming typical client device transmit powers (such as 20–30 mW), a power level around 10 mW (option A) would be appropriate, as it represents half of a typical client’s maximum transmit power and provides a suitable margin to manage interference and maintain location accuracy. Correct answer: A. 10 mW

No idea why cisco asks this kind of questions. No resources available on this topic.

any comments here? Thx

more sense?