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Question 81. What happens as directional antenna gain increases

1. Coverage angle becomes wider
2. Radio power disappears
3. Frequency changes automatically
4. Coverage becomes more focused

Correct Answer: 4. Coverage becomes more focused

Explanation:

Higher gain directional antennas concentrate more radio frequency energy into a narrower coverage area. As antenna gain increases, the radiation angle generally decreases while useful coverage distance in the intended direction can increase. This makes directional antennas suitable for locations such as long warehouse aisles, outdoor bridges, or areas where designers need to limit RF energy outside the target space. The antenna does not create additional transmitter power. Instead, it redirects available energy. High gain directional antennas must also be aimed accurately because their narrower beam makes placement and alignment more important.

Question 82. What coverage pattern does an omnidirectional antenna generally provide

1. Narrow forward beam
2. Coverage around the antenna
3. Coverage in one direction only
4. No horizontal coverage

Correct Answer: 2. Coverage around the antenna

Explanation:

An omnidirectional antenna is designed to provide coverage around the antenna in the horizontal plane. Cisco describes its radiation pattern as roughly doughnut shaped. This makes omnidirectional antennas practical for typical offices and other areas where users can approach the access point from many directions. Most access points with integrated antennas use an omnidirectional design unless otherwise specified. Increasing the gain of an omnidirectional antenna tends to flatten and focus the pattern rather than creating power. Directional antennas are more suitable when RF energy must be concentrated toward one specific area.

Question 83. Which antenna type is usually best for a long warehouse aisle

1. Directional antenna
2. Omnidirectional antenna
3. Isotropic antenna
4. Embedded Bluetooth antenna

Correct Answer: 1. Directional antenna

Explanation:

A directional antenna is usually well suited to a long warehouse aisle because its radio frequency energy can be focused along the aisle instead of spreading broadly into adjacent areas. This can increase useful coverage distance and reduce unwanted overlap with neighboring aisles. Antenna choice should still consider mounting height, aisle length, client devices, shelving, reflections, and expected capacity. As directional antenna gain increases, the coverage beam generally becomes narrower, so accurate aiming becomes increasingly important. Wireless design should select an antenna pattern that matches the physical shape of the required coverage area.

Question 84. What does EIRP represent in wireless design

1. Client association count
2. Channel utilization only
3. Effective radiated transmit power
4. Controller processing power

Correct Answer: 3. Effective radiated transmit power

Explanation:

EIRP represents the effective power radiated by a wireless system after transmitter power, antenna gain, and applicable losses are considered. It is important because regulatory authorities limit allowed radiated power according to frequency band and regulatory domain. A higher gain antenna can increase EIRP even when the access point transmitter power is unchanged. Cisco controllers account for antenna gain when determining actual radiated power so deployments remain within regulatory limits. Wireless designers should therefore evaluate transmitter power and antenna characteristics together rather than treating them as independent design variables.

Question 85. What is the main purpose of DFS in 5 GHz wireless networks

1. Increase client passwords
2. Protect radar systems
3. Disable channel reuse
4. Configure DHCP

Correct Answer: 2. Protect radar systems

Explanation:

Dynamic Frequency Selection allows wireless systems to use certain 5 GHz channels that are shared with radar systems while protecting those radar services from harmful interference. Access points operating on DFS channels must detect qualifying radar events and move away from the affected channel when required. DFS channels provide additional spectrum and can improve channel reuse, particularly in dense deployments. However, radar events can cause channel changes, so designers should understand the environment and application sensitivity before relying heavily on DFS channels for critical wireless coverage.

Question 86. Why are 20 MHz channels useful in high density deployments

1. They eliminate all interference
2. They double antenna gain
3. They increase AP transmit power
4. They provide more channel reuse

Correct Answer: 4. They provide more channel reuse

Explanation:

Using 20 MHz channels provides more independent channels for reuse than wider channel widths. This is important in high density deployments because many access points must share the available spectrum. Wider channels can provide higher theoretical throughput for an individual client, but they consume more spectrum and reduce the number of channels available for neighboring cells. Cisco recommends considering 20 MHz channels where access point and client density is high because improved frequency reuse can reduce cochannel interference and increase overall network capacity.

Question 87. What is a drawback of using 80 MHz channels in a dense WLAN

1. Clients cannot roam
2. APs lose PoE
3. Fewer independent channels are available
4. Authentication stops working

Correct Answer: 3. Fewer independent channels are available

Explanation:

An 80 MHz channel combines several narrower channels into one large channel. This can improve the maximum throughput available to an individual client, but it reduces the number of separate channels available for reuse. In a dense deployment with many access points, this can increase cochannel contention because more nearby radios must share the same wide channel. Cisco notes that wide channels can therefore reduce overall network performance in high density environments even though individual connection speeds appear attractive. Channel width should be selected according to capacity and reuse requirements rather than maximum theoretical speed alone.

Question 88. What does antenna front to back ratio describe

1. Rejection of signals behind the antenna
2. Number of supported clients
3. Maximum channel width
4. Switch power consumption

Correct Answer: 1. Rejection of signals behind the antenna

Explanation:

Front to back ratio describes how strongly a directional antenna favors the intended forward direction compared with the opposite direction. A useful front to back ratio allows designers to focus wireless coverage into the target area while reducing RF energy behind the antenna. This can help isolate cells and limit interference with nearby wireless areas. Cisco identifies front to back behavior as an important antenna property along with gain. The correct antenna pattern can therefore improve both coverage and frequency reuse when access points must serve specific physical spaces.

Question 89. What is a key 5 GHz design advantage over 2.4 GHz

1. Longer range in every environment
2. No attenuation through walls
3. Unlimited transmit power
4. More available channels

Correct Answer: 4. More available channels

Explanation:

The 5 GHz band provides more usable channels than the 2.4 GHz band, giving wireless designers greater flexibility for channel reuse and capacity planning. This is especially valuable in enterprise environments with many access points. Additional DFS channels can further increase the available 5 GHz spectrum where regulations permit their use. The larger channel set helps reduce situations where neighboring access points must use the same channel. However, designers must still account for propagation, interference, client support, regulatory requirements, and the selected channel width when creating the final RF plan.

Question 90. Which 2.4 GHz channels are commonly used for nonoverlapping design in the United States

1. Channels 1 6 and 11
2. Channels 2 7 and 12
3. Channels 3 8 and 13
4. Channels 1 5 and 9

Correct Answer: 1. Channels 1 6 and 11

Explanation:

Channels 1, 6, and 11 are commonly used for 2.4 GHz planning in regulatory domains where those three channels provide the standard nonoverlapping 20 MHz channel pattern. Using overlapping nearby channels can create adjacent channel interference and reduce network performance. Because 2.4 GHz offers limited spectrum, channel reuse must be planned carefully, especially when many access points are deployed. Modern enterprise designs often encourage capable clients toward 5 GHz or 6 GHz where more channel capacity is available, while retaining 2.4 GHz where client or coverage requirements justify it.

Question 91. Why should AP transmit power not greatly exceed client transmit power

1. It disables the controller
2. It can create an asymmetric RF link
3. It prevents all roaming
4. It changes the SSID

Correct Answer: 2. It can create an asymmetric RF link

Explanation:

Wireless communication is bidirectional. A client may hear a high power access point at a long distance while lacking enough transmit power to send reliable frames back to that AP. This creates an asymmetric link where downlink signal appears strong but uplink performance is poor. High AP power can also attract clients away from closer access points and produce uneven association distribution. Cisco design guidance recommends balanced transmit power planning rather than simply maximizing AP output. The cell should reflect the capabilities of the clients expected to use the network.

Question 92. What can disabling low wireless data rates help reduce

1. PoE power
2. Controller licenses
3. Oversized cell coverage
4. Wired bandwidth

Correct Answer: 3. Oversized cell coverage

Explanation:

Lower wireless data rates can be decoded at lower signal levels and therefore remain usable at greater distances. Disabling unnecessary low rates reduces the effective logical cell size and can improve frequency reuse in dense deployments. It also reduces airtime consumed by slow transmissions and management traffic sent at low mandatory rates. Cisco recommends carefully evaluating client compatibility before removing rates because older devices may require them. In well designed high performance networks, disabling low rates can improve roaming behavior, reduce cochannel contention, and increase overall airtime efficiency.

Question 93. What unit is commonly used to describe antenna gain

1. dBi
2. Mbps
3. Volts
4. Hertz

Correct Answer: 1. dBi

Explanation:

Antenna gain is commonly expressed in dBi, which compares the antenna radiation pattern with a theoretical isotropic radiator. Higher gain does not mean that the antenna generates additional RF power. Instead, the antenna focuses the available energy more strongly in selected directions while reducing it elsewhere. Cisco wireless documentation uses dBi when describing omnidirectional and directional antenna gain. Designers combine antenna gain with transmitter power and cable loss when considering radiated power, coverage, regulatory compliance, and the expected shape of the wireless cell.

Question 94. What can high antenna gain do to the beam width of a directional antenna

1. Make it wider
2. Remove the beam
3. Make it omnidirectional
4. Make it narrower

Correct Answer: 4. Make it narrower

Explanation:

As directional antenna gain increases, the radiation pattern generally becomes narrower and more concentrated. This can extend useful coverage distance in the intended direction while reducing the angle of coverage. High gain directional antennas can therefore be effective for bridge links, warehouse aisles, or targeted high density areas. The narrower beam also increases the importance of accurate antenna aiming. Poor alignment can leave the intended area outside the strongest portion of the pattern. Antenna selection should therefore consider both desired distance and required coverage angle.

Question 95. What is the purpose of channel reuse in wireless design

1. Use every AP on one channel
2. Reuse channels with sufficient RF separation
3. Disable automatic channel selection
4. Increase DHCP availability

Correct Answer: 2. Reuse channels with sufficient RF separation

Explanation:

Channel reuse allows the same wireless channel to be used by multiple access points when those cells are sufficiently separated so their contention and interference remain acceptable. Because available spectrum is limited, large wireless networks cannot assign a permanently unique channel to every access point. Good RF design therefore creates a channel reuse pattern that balances coverage and capacity. Excessive overlap between same channel cells increases cochannel contention because devices must share airtime. Channel width, transmit power, antenna pattern, physical placement, and RRM behavior all influence how effectively channels can be reused.

Question 96. Which channel width does Cisco commonly recommend for high density environments

1. 160 MHz
2. 80 MHz
3. 20 MHz
4. 320 MHz

Correct Answer: 3. 20 MHz

Explanation:

Cisco commonly recommends 20 MHz channels when access point and client density is high because the narrower width preserves more channels for frequency reuse. Wider channels can increase throughput for one client but consume more spectrum, resulting in more nearby access points sharing the same channel. This can increase contention and lower aggregate network capacity. Cisco guidance contrasts high density environments with deployments where maximum client throughput is more important and wider channels can be practical. Designers should choose channel width based on overall network capacity rather than only individual connection speed.

Question 97. What should AP power planning consider in addition to coverage

1. Browser type
2. Client transmit capability
3. DNS zone size
4. Controller password

Correct Answer: 2. Client transmit capability

Explanation:

Access point power planning should account for the transmit capability of expected client devices. Wireless links require communication in both directions, and many mobile clients transmit at less power than enterprise access points. If the AP cell is designed only around strong downlink power, clients near the edge may hear the AP but cannot send frames back reliably. This creates asymmetric communication and poor performance. Cisco also recommends power balance among neighboring APs so one high power radio does not attract too many clients compared with surrounding access points.

Question 98. What can excessive EIRP cause in an indoor WLAN

1. Oversized RF cells
2. Additional nonoverlapping channels
3. Lower antenna gain automatically
4. More switch ports

Correct Answer: 1. Oversized RF cells

Explanation:

Excessive radiated power can create cells that extend much farther than the design requires. Large cells can increase overlap between access points, create cochannel contention, attract clients to distant APs, and reduce frequency reuse. Very high EIRP can also violate regulatory limits when antenna gain is not considered correctly. Wireless design should therefore balance transmitter power and antenna gain according to coverage, capacity, client capability, and local regulations. More power is not automatically better. In dense networks, controlled cell size is often more valuable than maximum coverage distance.

Question 99. Why are DFS channels useful in a 5 GHz design

1. They eliminate client authentication
2. They remove all radar requirements
3. They increase switch capacity
4. They increase available channel capacity

Correct Answer: 4. They increase available channel capacity

Explanation:

DFS channels expand the pool of 5 GHz spectrum that can be used by wireless access points. This can significantly improve frequency reuse and capacity, especially when wider channels or many access points are required. Without DFS, the available channel set can be much smaller. The tradeoff is that access points using DFS channels must monitor for protected radar systems and leave the affected channel when radar is detected. Designers should therefore balance the capacity benefits of DFS with the application impact of possible channel changes and the regulatory requirements of the deployment region.

Question 100. What must an AP do after valid radar is detected on a DFS channel

1. Increase transmit power
2. Ignore the radar
3. Vacate the affected channel
4. Disable authentication

Correct Answer: 3. Vacate the affected channel

Explanation:

An access point operating on a DFS channel must vacate that channel when valid radar is detected according to regulatory requirements. The wireless system selects another permitted channel and clients must transition with the AP. This protects radar systems that have priority use of the shared frequency range. Cisco provides mechanisms such as channel announcements to reduce client disruption during the move, but applications can still experience some interruption. Designers using DFS should understand the likelihood of radar events in the environment and consider providing adequate non DFS channel availability where application continuity is especially important.