📘 Free 300-425 Sample Questions
A network engineer is preparing for an office site survey with a height of 2.5 meters. Which three components are
recommended to complete the survey? (Choose three.)
A
Use a battery pack to power APs.
B
Use a drawing of the office space to draw AP and client placements.
C
Use DoS attack on APs while measuring the throughput.
D
Use APs with directional antennas.
E
Use APs with external antennas.
F
Use APs with built-in antennas.
Correct Answer:
A. Use a battery pack to power APs.
Explanation:
The correct answer is A, B, and F. Let's break down why each selection is appropriate for an office site survey
with a 2.5-meter ceiling height.
A. Use a battery pack to power APs: This is crucial because during a site survey, you are likely moving access
points (APs) around to test different placements. Having a portable power source like a battery pack
eliminates the need for temporary power cords, which would be cumbersome and impractical. This facilitates
flexible and efficient testing during the survey process, mimicking a real-world scenario.
B. Use a drawing of the office space to draw AP and client placements: A floor plan serves as a visual guide.
You'll mark the locations of potential APs and client devices on this plan. This visual representation aids in
planning AP coverage, identifying potential signal obstructions, and allows for documentation of the optimal
placements. This enables easier analysis post-survey, for both present purposes and for later modifications of
the network design.
F. Use APs with built-in antennas: Built-in, omnidirectional antennas are ideal for initial site surveys. They
provide a relatively consistent signal in all directions, enabling an accurate assessment of coverage patterns
without directional limitations. This allows for better overall coverage assessment, and is crucial for
understanding general signal propagation within a defined space, particularly one where the ceilings are low
such as the 2.5m mentioned. Using these also eliminates the added complexity of potentially attaching and
removing external antennas during multiple testing phases.
Here's why the other options are unsuitable:
C. Use DoS attack on APs while measuring the throughput: Performing a Denial-of-Service attack is a
destructive testing methodology inappropriate for a site survey focused on optimal AP placement for
coverage. DoS attacks would artificially degrade the environment and not provide insight into the actual use
case. This should be part of security and load testing after the network is deployed, not during site surveys.
D. Use APs with directional antennas: While directional antennas have their place, they are generally not
appropriate for an initial site survey. Directional antennas focus the signal in one direction. This limits the
ability to assess general coverage patterns for the entire space and requires many more testing iterations.
These are generally used in environments with long, open spaces.
E. Use APs with external antennas: Similar to D, external antennas might be used later to fine-tune coverage.
However, built-in antennas provide a good starting point, a more simplified setup during surveys, and allow for
a more general assessment. While external antennas may be required for specific situations, for a site survey
where broad coverage testing is essential, they are generally unsuitable.
Authoritative links for further research:
Cisco Wireless LAN Controller (WLC) Configuration Best Practices:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-
5/b_Cisco_Wireless_LAN_Controller_Configuration_Best_Practices.html (While not specifically about site
surveys, it includes details on antenna types and wireless design considerations)
An engineer is designing a wireless network that will support many different types of wireless clients. When
conducting the survey, which client must be used to ensure a consistent experience for all of the wireless clients?
A
the client that has the highest RF properties
B
the client that is used most by the company
C
the client that is used least by the company
D
the client with the worst RF characteristics
Correct Answer:
B. the client that is used most by the company
Explanation:
The correct answer is D. the client with the worst RF characteristics.
Here's the justification: When designing a wireless network to support diverse clients, focusing on the client
with the weakest RF capabilities is crucial. This approach ensures that even the most challenging devices can
maintain a stable and usable connection. If the network is optimized for the best-performing client, devices
with inferior RF properties might suffer from poor performance, dropped connections, or an unusable
experience. By designing around the weakest link, we effectively build a network that can accommodate a
wide range of clients effectively. This practice is related to the concept of "worst-case scenario" planning,
infrastructure that meets the needs of all clients.
Authoritative Links:
wireless design.)
aiming to provide a baseline of good performance. Using the "weakest client" as the benchmark will provide
better performance for all the other clients. If you make a good experience for the most challenging client,
you will have an even better experience for the better ones. The process involves using survey tools to assess
the performance of the weakest client throughout the target environment, thus identifying coverage dead
spots and interference. This allows for the placement of access points to ensure a consistent level of service
across the entire area for all devices. This approach is particularly relevant in enterprise environments where
a variety of devices, including older models with lower capabilities, may be in use. By catering to the least-
capable client, you are effectively future-proofing the design. This strategy reduces the need for constant re-
optimization and ensures that no client is left underserved. The goal is to create a reliable and robust wireless
Cisco Wireless Design Best Practices: https://www.cisco.com/c/en/us/solutions/small-business/resource-
center/networking/wireless-design-best-practices.html (This Cisco page provides general guidance on
CWNP (Certified Wireless Network Professional) Resources: https://www.cwnp.com/ (CWNP offers
extensive information on wireless design principles.)
IEEE 802.11 Standards: https://www.ieee.org/ (While very technical, this is the source for Wi-Fi standards,
which dictate many RF behaviors)
An engineer has performed a predictive site survey for high-speed data and voice in an indoor office. What is the
recommended data rate with 67'a dBm signal level for optimal VoWLAN design?
A
6 Mbps on 802.11 bgn
B
24 Mbps on 802.11 bgn
C
12 Mbps on 802.11 an
D
24 Mbps on 802.11 an
Correct Answer:
C. 12 Mbps on 802.11 an
Explanation:
The correct answer is C. 12 Mbps on 802.11 an. Here's why:
For optimal VoWLAN (Voice over WLAN) design, maintaining a stable and reliable connection is paramount.
While higher data rates are desirable for general data traffic, voice applications are more sensitive to latency
and packet loss. Therefore, a balanced approach is needed.
A signal level of -67 dBm is considered acceptable for voice applications. However, at this level, pushing for
the highest possible data rate might lead to instability and packet loss, which would negatively impact voice
quality. 802.11a/n operates in the 5GHz band, generally less congested than the 2.4GHz band of 802.11b/g/n.
This makes it a preferable choice for voice traffic.
option at -67dBm than trying for higher rates.
Authoritative Links for Further Research:
While 24 Mbps (options B and D) might seem desirable, attempting that rate at a -67dBm signal might result
in decreased reliability. 6 Mbps (option A) would be insufficient for modern voice applications. Therefore, 12
Mbps on 802.11an (option C) represents a good compromise, providing adequate throughput with reasonable
reliability at the given signal strength, especially in a possibly congested environment. It allows a good
balance between speed and stability, ensuring a better voice experience. Using 802.11n in 5 GHz allows for
the use of features that improve voice quality, such as shorter intervals.
In conclusion, the goal is to choose a rate that provides both sufficient bandwidth and reliable connectivity for
voice calls within the given signal constraints. 12 Mbps on 802.11 an offers a more stable and dependable
Cisco Wireless Voice Design Guide: Although a specific document varies, searching for "Cisco wireless voice
design guide" on cisco.com will provide valuable and current recommendations and best practices.
IEEE 802.11 Standards: Refer to the official IEEE 802.11 standards documents for in-depth technical
information about WiFi protocols and their capabilities (available via IEEE Xplore). https://ieeexplore.ieee.org/
A customer is concerned about mesh backhaul link security. Which level of encryption does the backhaul link use?
A
hash
B
AES
C
WEP
D
3DES
Correct Answer:
B. AES
Explanation:
The correct answer is B. AES (Advanced Encryption Standard). Cisco mesh networks, including the backhaul
links, utilize robust encryption to ensure data confidentiality and integrity. While various encryption methods
exist, AES is the industry-standard choice for its strong security and efficiency. Option A, hash, is not an
encryption algorithm; instead, it's a one-way function used for data integrity checks and password storage,
but not for link encryption. Options C, WEP (Wired Equivalent Privacy) and D, 3DES (Triple Data Encryption
Standard), are older encryption methods considered weak and vulnerable to attacks; they are not used for
modern Cisco mesh backhaul security. AES, specifically AES-CCMP (Counter Cipher Mode with Block
Chaining Message Authentication Protocol), is implemented for secure communication between mesh access
points in Cisco wireless deployments. This ensures that data transmitted over the backhaul is protected from
eavesdropping and tampering. Cisco's wireless documentation emphasizes the use of AES as the standard
encryption for secure mesh links. Therefore, AES provides the necessary strong encryption required for
backhaul link security in Cisco enterprise wireless networks.
Relevant Resources:
Cisco Wireless Mesh Design Guide: https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-
5/b_mesh_design_guide/b_mesh_design_guide_chapter_010.html (Look for sections on security and
encryption within mesh deployments)
Cisco Validated Design for Wireless: https://www.cisco.com/c/en/us/solutions/enterprise/design-
zone/wireless-design.html (This provides broader information on wireless design and security, though specific
security details are often within product documentation)
NIST publication on AES: https://csrc.nist.gov/publications/detail/fips/197/final (Provides authoritative source
on AES standards)
As part of a wireless site survey in a hospital, an engineer needs to identify potential Layer 1 interferers. In which
two areas is the engineer most likely to find sources of 2.4 GHz and 5 GHz RF noise? (Choose two.)
A
magnetic resonance imaging
B
kitchen
C
Gamma Knife radiation treatment
D
X-ray radiography
E
patient room
Correct Answer:
B. kitchen
Explanation:
The correct answer is B. kitchen and E. patient room. These areas are highly likely to contain devices that
emit RF noise within the 2.4 GHz and 5 GHz bands, which are commonly used by Wi-Fi.
Kitchens (B) often house microwave ovens, which operate at 2.4 GHz. Although designed to contain radiation,
some leakage is possible, causing interference. Bluetooth devices, frequently used in smart kitchen
appliances and personnel's headsets, also operate in the 2.4 GHz range. Additionally, some older cordless
phones might also utilize these frequencies. Thus, kitchens present a concentrated risk of 2.4 GHz
interference.
Patient Rooms (E) represent a diverse environment. While medical devices are designed to minimize
interference, some might operate at or near Wi-Fi frequencies or emit spurious noise. Moreover, personal
electronics like smartphones, tablets, and laptops, which actively use Wi-Fi (both 2.4 GHz and 5 GHz) and
Bluetooth, are prevalent in patient rooms. These devices can become a collective source of RF noise,
degrading Wi-Fi performance. Furthermore, bedside monitoring devices might use wireless links for data
transmission, which could also introduce interference if not managed carefully. These various sources,
common in patient rooms, contribute to potential RF congestion and noise.
Magnetic Resonance Imaging (MRI) (A) and Gamma Knife radiation treatment (C) emit significantly higher
frequencies, falling outside the 2.4 GHz and 5 GHz range used by Wi-Fi. X-ray radiography (D), while also
involving radiation, primarily operates in significantly higher frequency ranges than those relevant to Wi-Fi,
making them unlikely sources of interference in the 2.4 and 5 GHz bands. Therefore, these three options are
incorrect in this context.
In summary, kitchens and patient rooms are the primary areas within a hospital environment where engineers
are likely to encounter significant sources of 2.4 GHz and 5 GHz RF noise due to the prevalence of microwave
ovens, personal electronics, and Bluetooth-enabled devices. These findings are crucial when planning and
executing Wi-Fi site surveys.
Supporting Links:
operation).
IEEE 802.11 (Wi-Fi) Standards: https://www.ieee802.org/11/ (Information on Wi-Fi frequency bands and
Interference Sources: https://www.wi-fi.org/knowledge-center/blog/understanding-interference-and-its-
impact-wi-fi-performance (General information about common interference).
Radio Frequency Interference: https://www.fcc.gov/consumers/guides/radio-frequency-interference-basics
(FCC guide on radio frequency interference.)
Which three pieces of equipment are needed to conduct a fully measured wireless survey? (Choose three.)
A
PoE battery
B
spirit level
C
access point
D
tall tripod
E
goggles
F
ladder
Correct Answer:
A. PoE battery
Explanation:
Let's dissect why options A, C, and D are the correct choices for a measured wireless survey, while B, E, and F
are not. A PoE battery (A) is essential because it provides portable power to the access point, allowing the
surveyor to take measurements at various locations without being tethered to a wall outlet. This mobility is
crucial for accurately mapping wireless coverage in a real-world environment. A spirit level (B) is irrelevant to
wireless surveying, as it's used for ensuring surfaces are horizontally level. An access point (C) is
fundamental; it generates the wireless signals that are measured, enabling the survey to assess coverage,
signal strength, and other vital wireless network characteristics. A tall tripod (D) is necessary to secure the
access point at the optimal height for measurement, preventing ground interference and enabling consistent,
accurate data capture. Goggles (E) and a ladder (F) are not required for a wireless survey, as the process
typically doesn't involve risks requiring protective eyewear or reaching high locations. Thus, the combination
of a portable power source (PoE battery), the core signal transmitter (access point), and a mounting solution
(tall tripod) is necessary for an effective measured wireless survey. These tools allow for a systematic and
accurate assessment of the wireless network environment, crucial for deployment and optimization of
enterprise wireless solutions.
For further research, consider resources like:
Cisco's official documentation on wireless design and surveys:
https://www.cisco.com/c/en/us/solutions/enterprise-networks/wireless-lan-networking/index.html
CWNP (Certified Wireless Network Professional) resources: https://www.cwnp.com/
Article on conducting Wi-Fi surveys: https://www.ekahau.com/blog/how-to-perform-a-wifi-site-survey-the-
definitive-guide/
When conducting a site survey for real-time traffic over wireless, which two design capabilities of smartphones
and tablets must be considered? (Choose two.)
A
no support for 802.11ac
B
higher data rates than laptops
C
fewer antennas than laptops
D
no support for 802.11r
E
lower data rates than laptops
Correct Answer:
C. fewer antennas than laptops
Explanation:
Here's a detailed justification for choosing options C and E as the correct answers when considering real-time
wireless traffic during a site survey involving smartphones and tablets:
Justification:
Smartphones and tablets, unlike laptops, typically have fewer antennas (C). This design constraint directly
impacts their ability to utilize Multiple-Input Multiple-Output (MIMO) technology effectively. MIMO, a key
feature in modern Wi-Fi standards, relies on multiple antennas to transmit and receive data simultaneously,
enhancing throughput and range. Devices with fewer antennas experience reduced spatial streams, thus
limiting potential data rates and potentially affecting the quality of real-time applications (e.g., voice, video).
This makes accurate assessment of signal strength and coverage, especially for densely populated areas
using these devices, crucial during a site survey.
Furthermore, smartphones and tablets generally have lower data rates than laptops (E) due to a variety of
factors, including antenna limitations, power constraints, and processing capabilities. While they support Wi-
Fi standards like 802.11ac (and now 802.11ax/Wi-Fi 6), their effective throughput is often lower than that of
laptops due to a smaller number of antennas. This impacts their suitability for latency-sensitive applications.
Overloading a wireless network with a high number of these devices running resource-intensive, real-time
applications without proper planning may lead to poor quality and service interruptions. Consequently, this
difference in capabilities needs to be accounted for in the network design, potentially requiring more Access
Points (APs) to accommodate the traffic load adequately and provide a smooth user experience.
Options A and D are generally incorrect, as most modern smartphones and tablets do support 802.11ac and
802.11r respectively. Option B is incorrect because laptops generally have higher potential data rates due to
their greater number of antennas and often more powerful processing capabilities. Therefore, recognizing the
constraints of fewer antennas and lower data rate capabilities in smartphones and tablets during a site survey
is essential for properly designing a reliable wireless network that meets the demands of real-time traffic.
Authoritative Links for further research:
Cisco Wireless Design Guide: https://www.cisco.com/c/en/us/solutions/enterprise/design-zone/wireless-
design-guide.html
Understanding MIMO: https://www.intel.com/content/www/us/en/tech-tips-and-tricks/what-is-mimo-
wifi.html
802.11 Standards: https://www.wi-fi.org/knowledge-center/wi-fi-certified-standards
Which two criteria must be considered when conducting an outdoor bridge site survey? (Choose two.)
A
near-far effect
B
weather
C
traffic lights
D
power lines
E
Fresnel zone
Correct Answer:
B. weather
Explanation:
The correct answer is B (weather) and E (Fresnel zone). When planning outdoor wireless bridge links, a site
survey must meticulously consider environmental factors. Weather significantly impacts signal propagation.
Rain, fog, and snow can attenuate radio waves, causing signal degradation or complete loss, particularly at
higher frequencies. Therefore, assessing typical weather conditions at the site is critical for reliable
performance.
The Fresnel zone is another essential factor. This elliptical area surrounding the direct line of sight between
two antennas must be largely free of obstructions to avoid significant signal reflections and attenuation.
Supporting Links:
Cisco Wireless Design Guide:
Fresnel zone)
Obstructions within the Fresnel zone, such as trees, buildings, or hills, can cause multipath interference and
reduced signal strength. Ignoring this aspect will result in inconsistent and unreliable connections.
The near-far effect (A) is more relevant to wireless access networks with multiple clients sharing a single
access point rather than point-to-point bridge links. Traffic lights (C) are generally irrelevant unless they are
acting as a physical obstruction. Power lines (D), though potentially causing interference, are not as
fundamental as weather and Fresnel zone considerations when designing a successful wireless bridge link.
Ignoring the Fresnel zone and local weather conditions can lead to signal instability and connectivity issues,
even with powerful hardware. A thorough analysis of weather patterns and the Fresnel zone using appropriate
tools and calculations is necessary to achieve a stable and robust wireless bridge.
https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/emob41dg/emob41_DG-
book/ch3_rfplan.html (This is a general RF planning guide, but relevant to understanding concepts like
Outdoor Wireless Bridge Best Practices: Search for articles or documentation related to outdoor wireless
bridge link design and best practices to find resources further explaining Fresnel zone and weather
considerations
An engineer is performing a predictive wireless design for a medical treatment environment, which requires data
and voice services. What is the minimum requirement for the design?
A
overlapping 72"a dBm coverage from two access points
B
continuous 67'a dBm coverage from one access point
C
continuous 72"a dBm coverage from one access point
D
overlapping 67'a dBm coverage from two access points
Correct Answer:
D. overlapping 67'a dBm coverage from two access points
Explanation:
The correct answer, D, specifying overlapping -67 dBm coverage from two access points, aligns with best
practices for designing robust wireless networks, especially in critical environments like medical treatment
facilities requiring voice and data. Voice over Wi-Fi (VoWiFi) demands a higher signal-to-noise ratio (SNR) than
typical data applications to ensure call quality and avoid dropped connections. Achieving this requires not just
a strong signal, but also redundancy through overlapping coverage.
A signal strength of -67 dBm is generally considered the minimum threshold for reliable voice and data
communication, offering a balance between performance and cell size. Relying on a single access point (AP),
as options B and C suggest, creates a single point of failure and lacks the robustness needed for critical
applications. Overlapping coverage from at least two APs ensures that if one AP fails or experiences
interference, the client can seamlessly roam to another AP, maintaining connectivity and minimizing
disruption. Option A, using -72 dBm, provides weaker signal, which may cause significant performance
degradation, especially with voice.
Overlapping coverage also provides better support for client roaming, as clients can smoothly transition
between APs with minimal packet loss. This is essential for uninterrupted voice calls as users move through
the environment. Furthermore, a stronger signal of -67 dBm (-67dbm), compared to a signal of -72dbm
(-72dbm), will reduce packet retransmissions, leading to better overall network efficiency. In conclusion,
overlapping -67 dBm coverage from two access points offers the redundancy and signal quality needed for
reliable voice and data services in a medical treatment environment.Authoritative Links:
Cisco Wireless Design Best Practices:
https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-
5/b_Cisco_Wireless_Design_Best_Practices.html
Cisco - RF Design for Voice over Wireless LAN:
https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-wlan/106006-rf-design-voice.html
CWNP - Understanding RF Math: https://www.cwnp.com/rf-math/ (This link helps in understanding the
significance of dBm values).
Which non-Wi-Fi interferer can be identified by Metageek Chanalyzer?
A
PDAs
B
jammers
C
smartphones
D
printers
Correct Answer:
B. jammers
Explanation:
The correct answer is B. jammers. Metageek Chanalyzer is a spectrum analyzer tool used to visualize and
analyze radio frequency (RF) signals. It excels at identifying various sources of interference, specifically those
operating within the same frequency bands as Wi-Fi (2.4 GHz and 5 GHz). While devices like PDAs,
smartphones, and printers may emit RF signals, they generally do so on different frequencies or with
protocols not typically considered Wi-Fi interference (e.g., Bluetooth, NFC, or USB). Jammers, on the other
hand, are explicitly designed to transmit strong RF signals to disrupt or block legitimate communication,
including Wi-Fi. Chanalyzer can detect the characteristic wideband or narrowband RF signatures of
intentional jammers, making them a significant source of interference that the tool can identify. It can discern
the distinct behavior of jamming signals from normal Wi-Fi usage. The tool uses techniques such as waterfall
diagrams and spectrum density graphs to showcase the frequency and intensity of RF activity, allowing
network administrators to pinpoint the presence of disruptive jammers within the wireless environment. This
analysis is crucial for effective troubleshooting and mitigation of wireless performance problems. Jammers
actively and intentionally create problems for other RF signals, and their purpose makes them stand out
among other sources of interference.
Authoritative Links:
Metageek: https://www.metageek.com/ (Official website for information about Chanalyzer)
Metageek Chanalyzer Documentation: https://support.metageek.com/hc/en-us/categories/200546967-
Chanalyzer (For detailed information about the tool's capabilities)
Understanding Wi-Fi Interference: https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-
wireless-controllers/114478-troubleshoot-wlan.html (Cisco resource on Wi-Fi troubleshooting, including
interference)
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