Which Mobile Device to Use for Active Site Survey?

300-425 By islever Editorial Last updated

Short answer

B Use the mobile device with the lowest receiver sensitivity for the active survey.

Question

An engineer is performing an active survey of a network that must support different types of mobile devices. The devices must be able to run an application that requires a minimum RF of 73 dBm. Which mobile device must be used for the survey?
  1. one that has a receiver sensitivity of -70 dBm
  2. one that has the lowest receiver sensitivity Correct Answer
  3. one that has the most updated wireless card
  4. one that has 802.11a wireless support

Key Takeaways

Tests the Cisco site survey rule of choosing the least sensitive client; the trap is confusing 'lowest receiver sensitivity' with the most sensitive (most negative) device.

When an application requires a minimum RF of -73 dBm, the active site survey must use the mobile device with the lowest receiver sensitivity to guarantee worst-case coverage. This page confirms option B and explains why a -70 dBm device is not the answer.

Common mistake: Many pick a device with -70 dBm sensitivity (A) because the number looks closer to -73 dBm, but -70 dBm is actually less sensitive and would require a stronger signal, failing to represent the worst-case client.

Expert Analysis

Why the Answer Is Correct

The question asks which mobile device must be used for an active survey when devices must run an application requiring a minimum RF of -73 dBm. Cisco design doctrine says to always survey with the least capable client—the one with the lowest receiver sensitivity—so that the resulting coverage meets the needs of every device. Option B captures this principle directly. Using the worst-case device ensures that if the survey passes at -73 dBm, all better-sensitivity devices will also work. Therefore B is correct.

Why the Other Options Are Wrong

Option A specifies a receiver sensitivity of -70 dBm, which is actually a stronger (less negative) threshold than -73 dBm; such a device would require a signal of at least -70 dBm to operate, so it could not validate the -73 dBm requirement and is not the worst-case client. Option C, a "most updated wireless card," is irrelevant because survey device selection hinges on RF sensitivity, not driver or card generation. Option D, 802.11a support, only addresses band capability and does not determine whether the device can accurately represent the minimum RF level for the application.

Community Comment Notes

As Bandito noted, option B "sounds more logical here" because the least capable device should be used. Bembs reinforces this as best practice, stating "Always consider the least capable device." Raptuz argues for option A, suggesting that a device with equal or slightly better sensitivity (e.g., -70 dBm) should be used if the survey must guarantee a minimum required RF level; however, that reasoning misreads -70 dBm as better when it is actually less sensitive than -73 dBm. Lakshan__97 adds that performing an active survey with a 3 dBm lower sensitivity might be fine, but the exam's standard answer remains the worst-case device.

Exam Strategy

Focus on the phrase 'must support different types of mobile devices'—it signals a worst-case design. Choose the option describing the least capable device, not the one that simply matches the -73 dBm number.

Frequently Asked Questions

Why not use a device with -70 dBm receiver sensitivity for the survey?

A -70 dBm device is less sensitive and needs a stronger signal than -73 dBm, so it cannot validate the minimum RF requirement or represent the worst-case client.

What does 'lowest receiver sensitivity' mean in Cisco site surveys?

It means the least sensitive client—the one with the highest dBm threshold—so you design for the device that needs the strongest signal.

More 300-425 FAQ →

Community Votes

B
67%
A
33%

67% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 4 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 4

  1. Bandito 👍 6
    B sounds more logical here. The least capable device should be used.
  2. Bembs 👍 4 Answered B
    Best practice. Always consider the least capable device
  3. raptuz 👍 1 Answered A
    If the survey needs to guarantee a minimum required RF level (e.g. -73 dBm), it is better to use a device that has equal or slightly better sensitivity (e.g. -70 dBm). If, on the other hand, a network is to be designed for devices with very weak receivers, then it makes sense to test with the least capable device.
  4. Lakshan__97 👍 1 Answered A
    i think perform an active survey with 3 dBm lower is fine

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