300-425 practice questions 161–170

1. Question 161 · 245 in bank

   Select 2

   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.)

   • Amagnetic resonance imaging
   • Bkitchen
   • CGamma Knife radiation treatment
   • DX-ray radiography
   • Epatient room

   Show answer

   Answer: BE

   Explanation

   This answer is right, even though I wasn't sure at first. MRI scans emit at a frequency of 1MHz-300MHz, which is below the frequency of Wi-Fi (2.4GHz and 5GHz). Gamma rays (Exahertz) and X-rays (Petahertz) are happening at frequencies much higher than RF as well. Kitchens can be source of 2.4GHz interference with microwave ovens. I have no clue what can cause RF noise in patient rooms, but by elimination, it works.

   Source: Adapted from community discussion — antmich

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2. Question 162 · 245 in bank

   A network engineer is designing a new wireless network. The network needs to have these characteristics: ✑ support high client concentration ✑ optimize client performance ✑ avoid interference Which approach should be taken?

   • ADeploy APs near each other for 2.4 GHz coverage, and disable the 5 GHz radios for all APs.
   • BDeploy APs near each other for 5 GHz coverage, and disable the 2.4 GHz radios for some APs.
   • CDeploy APs near each other for 2.4 GHz coverage, and disable the 5 GHz radios for some APs.
   • DDeploy APs near each other for 5 GHz coverage, and enable the 2.4 GHz radios for all APs.

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   Answer: B

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3. Question 163 · 245 in bank

   Why is 802.11a connectivity reduced in an X-ray room?

   • AX-rays create significant non-Wi-Fi interference on the 802.11a band.
   • BX-rays impact the 802.11a UNII-2 channels that cause access points to dynamically change channels.
   • CX-rays within these rooms cause multipath issues.
   • DX-ray rooms exhibit increased signal attenuation.

   Show answer

   Answer: D

   Explanation

   D its correct. According the book (...) d X-ray areas, where the walls might be lead-lined and completely stop RF signals.(...) Its not A because says:(...) These devices may also use the same spectrum as Wi-Fi but with other protocols and, therefore, become sources of interference for your system(...) It does not mention non-Wifi interference, it says the same Wifi spectrum.

   Source: Adapted from community discussion — Johnconnor2021

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4. Question 164 · 245 in bank

   What is the attenuation value of a human body on a wireless signal?

   • A3 dB
   • B4 dB
   • C6 dB
   • D12 dB

   Show answer

   Answer: A

   Explanation

   (a) 3 dB vhttps://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/71642-vocera-deploy-guide.html Plasterboard wall 3 dB Glass wall with metal frame 6 dB Cinder block wall 4 dB Office window 3 dB Metal door 6 dB Metal door in brick wall 12 dB Human body 3 dB

   Source: Adapted from community discussion — Gray99

   References

   • Cisco documentation
   • Cisco documentation

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5. Question 165 · 245 in bank

   During a wireless network design, a customer requires wireless coverage on the perimeter of a building but also wants to minimize signal leakage from the wireless network. Which antenna should be used to accomplish this design?

   • Aomnidirectional
   • Bpatch
   • Cmonopole
   • Ddipole

   Show answer

   Answer: B

   References

   • Cisco documentation
   • Cisco documentation

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6. Question 166 · 245 in bank

   An engineer at a global enterprise organization must ensure that a mesh deployment has the highest number of channels available to the backhaul, regardless of region deployed. Which design meets this requirement?

   • Aredundant controllers in the least restrictive regulatory domain
   • Bredundant controllers in the most restrictive regulatory domain
   • Cone controller per continent
   • Done controller per country code

   Show answer

   Answer: D

   Explanation

   D - AP regulatory domain is set when shipped, this can’t be changed. Country codes are changed manually on the WLC, not the regulatory domain. The country set must be in the regulatory domain of any associated APs. There is no setting for continent.

   Source: Adapted from community discussion — RogerTheLodger

   References

   • Cisco documentation

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7. Question 167 · 245 in bank

   A customer is looking for a network design with Cisco Hyperlocation using AP4800 for location tracking via a custom mobile app. Issues appeared in the past with refresh rates for location updates. What needs to be implemented to meet these requirements?

   • ACisco CMX SDK in the location app
   • Bdevice Bluetooth via the app
   • CCisco FastLocate technology
   • Dredundant CMX and fetch location in round-robin fashion

   Show answer

   Answer: C

   Explanation

   Implementing CMX SDK on the mobile app is not a part of the network design. Faster refresh from mobile devices result in drain of battery. Cisco Fastlocate needs to be enabled so that the location packets are read from the data packets and this is deployed on the Network. So Given answer is correct

   Source: Adapted from community discussion — santoshkotla

   References

   • Cisco documentation
   • Cisco documentation

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8. Question 168 · 245 in bank

   Select 2

   An engineer must perform an assessment of a customer LAN for a future IEEE 802.11ac Wave 2 wireless deployment. All access switches are Fast Ethernet- capable only, and the wired infrastructure between existing APs and access switches is based on the CAT 6A standard. Which two actions provide maximum support of Cisco 3800 Series access points? (Choose two.)

   • AReplace the existing switches with mGig switches.
   • BEnsure that cable distances between access switches and APs are not longer than 55 meters.
   • CReplace the existing switches with gigabit switches with 10 G uplinks.
   • DEnsure that cable distance between access switches and APs are not longer than 100 meters.
   • EReplace the existing wiring infrastructure with the CAT-7E wiring standard.

   Show answer

   Answer: AD

   Explanation

   AD - mGIG switches recommended for 802.11AC wave 2 AP deployment Cisco 802.11ac Wave 2 Access Points - Cisco CAT 6A cable can support mGIG links when they do not exceed 100m Cisco Aironet Series 2800/3800 Access Point Deployment Guide

   Source: Adapted from community discussion — RogerTheLodger

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9. Question 169 · 245 in bank

   A network engineer is working on a predictive WLAN design. The new wireless network must support access to Internet, email, voice, and the inventory database. To successfully support these services, which configuration must the engineer use for the signal strength levels and SNR on the planning tool?

   • Asignal strength of -67 dBm, 20-dB SNR, and maximum 5 percent packet loss
   • Bsignal strength of -70 dBm, 30-dB SNR, and maximum 10 percent packet loss
   • Csignal strength of 67 dBm, 20-dB SNR, and maximum 1 percent packet loss
   • Dsignal strength of -67 dBm, 25-dB SNR, and maximum 1 percent packet loss

   Show answer

   Answer: D

   Explanation

   Answer cannot be C, as the signal strength has a positive value. Answer is D as shown in official cert guide, page 106. 'When you need an AP deployment that supports voice and video, your goal should be to design for wireless coverage and call capacity. AP cells should be overlapped by about 20 percent to streamline client roaming and handoff from one AP to another. Any delay or interruption will be very noticeable to users on an active call, so devices should be able to find candidate APs well ahead of time as the users move around. As the previous sections recommended, the RSSI of each AP should be −67 dBm or higher at the boundary of its cell, and the SNR should be 25 dB or greater. When you perform an active site survey to validate the network’s performance, packet loss or the packet error rate (PER) should be no greater than about 1 percent.'

   Source: Adapted from community discussion — RogerTheLodger

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10. Question 170 · 245 in bank

    An engineer is designing a new wireless network. The network needs to meet these requirements: ✑ support a high wireless client concentration ✑ support data over wireless ✑ support voice over wireless ✑ avoid interference Which design approach should be taken?

    • A5 GHz frequency band with channel bonding, to support 40 MHz channels
    • B5 GHz frequency band without channel bonding, to support 20 MHz channels
    • C2.4 GHz frequency band without channel bonding, to support 20 MHz channels
    • D5 GHz frequency band with channel bonding, to support 80 MHz channels

    Show answer

    Answer: B

    Explanation

    B - to avoid interference you have to have a higher SNR as possible. While doing Channel bonding you add noise. Besides, high wireless clients concentration demand needs to have a high SNR and to avoid Co-Channel interference. I quote: "One of the hallmarks of a high-performing WLAN is channel reuse. This is the practice of deploying channels in such a manner that they limit the amount if CCI introduced into the environment. The best way to achieve this is by having as many channels to deploy as possible. While a 20MHz channel will not achieve the higher data rates that are advertised with 80MHz, clients can still reach acceptable speeds, allowing you to optimally use each bit of available airtime." https://www.ekahau.com/blog/channel-planning-best-practices-for-better-wi-fi/

    Source: Adapted from community discussion — Johnconnor2021

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300-425 practice, question 161. 245 questions available.