Predictive Site Survey Location-Ready AP Count

300-425 By islever Editorial Last updated

Short answer

D Deploy at least four access points per floor to meet Cisco's recommended standard for location-ready networks using HyperLocation.

Question

An engineer must design a predictive site survey. The wireless network must be “location-ready”. Each floor is quite small and has only a few offices. Which approach must be considered?
  1. At least two access points are deployed on each floor
  2. At least one access points are deployed on each floor.
  3. At least three access points are deployed on each floor.
  4. At least four access points are deployed on each floor. Correct Answer

Key Takeaways

Tests the specific Cisco design guideline for location services, distinguishing between the theoretical minimum (3 APs) and the recommended deployment standard (4 APs) for 'location-ready' designs.

Determines the minimum access point density required for location-ready wireless networks in small office environments. Establishes that Cisco HyperLocation requires at least four APs per floor for optimal accuracy.

Common mistake: Candidates often select 3 APs based on general trilateration theory, failing to recognize that Cisco's official recommendation for reliable location readiness specifies a minimum of 4 APs per floor.

Expert Analysis

Why the Answer Is Correct

Cisco's HyperLocation technology relies on RSSI-based trilateration to determine client positions. While three Access Points are theoretically sufficient to triangulate a position, Cisco explicitly recommends deploying at least four APs per floor to ensure redundancy, accuracy, and robust coverage. This ensures that if one AP is blocked or experiences interference, the system can still calculate location accurately using the remaining three. The question specifies a 'location-ready' network, which implies adhering to best-practice standards rather than just theoretical minimums.

Why the Other Options Are Wrong

Option A (2 APs) and Option B (1 AP) provide insufficient data points for any form of geometric positioning calculation. Option C (3 APs) represents the absolute mathematical minimum for trilateration but does not meet Cisco's operational recommendation for high-accuracy location services in a production environment. Selecting 3 APs risks poor performance when devices move between floors or when signal obstruction occurs.

Community Comment Notes

Community feedback highlights the nuance between theoretical requirements and vendor guidelines. User AdamNoe correctly cited the Cisco HyperLocation deployment guide recommending a minimum of 4 APs per floor. User Farhad123 noted that while -75dB thresholds might suggest 3 APs, the design phase for location readiness prioritizes staggering APs with a count of 4. User igaunas12 acknowledged that while 3 is the minimum, 4 is preferred for optimum accuracy, aligning with the exam's expectation for best practices.

Official Reference

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-8/b_ap_4800_hyperlocation_deployment_guide.html#id_81793

This link opens the official vendor documentation in a new tab.

Exam Strategy

When designing for 'location-ready' or 'HyperLocation' capabilities, always default to Cisco's recommended minimum of 4 APs per floor unless the question specifically asks for the theoretical minimum. Memorize that 3 is the math minimum, but 4 is the design standard.

Frequently Asked Questions

Why is 3 APs not the correct answer for location-ready?

While 3 APs allow for basic trilateration, Cisco recommends 4 APs per floor to ensure redundancy and higher accuracy for location services.

What is the difference between location-ready and full location service?

Location-ready implies the infrastructure supports it; Cisco mandates a minimum of 4 APs/floor to ensure this capability functions reliably in production.

More 300-425 FAQ →

Community Votes

D
57%
C
43%

57% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 7 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 7

  1. gargionifabio 👍 2 Answered D
    for a better accuracy location services, each device needs to be seen by at least 4 AP's
  2. igaunas12 👍 1 Answered C
    Minimum detected received signal thresholds—For mobile devices to be tracked properly, it is highly recommended that access points report mobile device RSSI to their respective controllers at levels meeting or exceeding the RSSI cutoff value that is configured in WCS. A minimum of three access points (and preferably four or more for optimum accuracy) should be reporting this level of signal strength or better for any device being localized. Mobile device RSSI reported below this level may be discarded by the location appliance. https://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob30dg/Locatn.html
  3. 55f2ace 👍 1 Answered C
    Guide: Location uses trilateration, which means that you need several APs around each point of your floor so that a location engine in the infrastructure can combine the signal these APs receive from each client and compute the client location. For each point of the floor, you need at least three surrounding APs.
  4. Farhad123 👍 1 Answered D
    tricky question , when a question is asking about -75dB client RSSI from X APs? the answer is 3 APs. But here the question is asking about design and placement then based on cisco recommendation we should try to stagger the APs and having 4 APs in each floor
  5. AdamNoe 👍 1 Answered D
    Basic Rule: Deploy minimum of 4 APs per floor https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-8/b_ap_4800_hyperlocation_deployment_guide.html#id_81793
Show 2 more comments
  1. Love2Cod3 👍 1 Answered C
    Location services require 3-4 APs. Here, the network must be “location-ready” so 3 APs/flr should be considered.
  2. Farhad123 👍 1
    C is correct

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