Question 1

You must provide the best coverage possible for users inside an office. The office is free from tall obstructions such as shelving, but has a high ceiling. You have decided to use a low-gain Omni-directional antenna to achieve your goal. Where should you install the antenna for best coverage?

Accepted Answer

For best coverage, the antenna should be installed in the center of the building on the ceiling.
Key Takeaway: In an open area where maximum user coverage is required, using a low-gain Omni antenna makes practical and economical sense. In this office that has high ceilings, use of a high-gain Omni-directional antenna might not be effective for users below the plane of the antenna. Hence, mounting a low-gain Omni-directional antenna near the center of the intended coverage like the ceiling is most effective.

Question 2

Which of the following security options are included in most wireless residential gateways?

Accepted Answer

Most wireless residential gateways include a VPN client.
Key Takeaway: The VPN client's pass-through functionality allows SOHO users to connect to a corporate VPN server over the Internet using a secure tunnel. Virtual servers must be manually configured by the administrator to direct packets to a particular server. This control allows the administrator to keep the internal servers secure.

Question 3

You are a consultant installing a wireless LAN that will connect two buildings that are 1.5 miles apart, with data transfer speeds of 11 Mbps. Which of the following antennas should you use?

Accepted Answer

You should use a High-gain Yagi antenna to connect two buildings that are 1.5 miles apart, with data transfer speeds of 11 Mbps.
Key Takeaway: Yagi antennas are most often used on short- to medium-length building-to-building bridging up to 3.3 km. It is a directional antenna system consisting of an array of a dipole and additional closely-coupled parasitic elements. The dipole in the array is driven and another element, typically 5% longer, effectively operates as a reflector.

Question 4

Why is it not advisable to have a number of access points in the repeater mode in a series?

Accepted Answer

It is not advisable to have a number of access points in repeater mode in a series since users attached to the access point in repeater mode will experience high latencies.
Key Takeaway: Repeaters can cause very high latencies for data transmissions, which may make some transmissions impossible to perform, such as real-time audio or video.

Question 5

You need to connect two wired networks together that currently share no network connectivity between them. Which mode would the access points need to be placed in if the networks use only access points to connect the networks?

Accepted Answer

The access points need to be placed in the Bridging mode if the networks use only access points to connect the networks.
Key Takeaway: When Access points serve in root or repeater mode, they allow only client connectivity. In this scenario, wireless bridges should be used. In the absence of a wireless bridge, many access points support a bridging mode, where the access points can effectively be a bridge that connects two segments together wirelessly.

Question 6

John is a consultant installing a wireless LAN that will connect four buildings that are 100 meters apart. Which of the following antennas should he use?

Accepted Answer

John should use 1 dipole and 3 patch antennas to install a wireless LAN that will connect four buildings that are 100 meters apart.
Key Takeaway: Although John can use 4 Omni-directional antennas, such as dipoles, in this short-range scenario, for security reasons, he should use a single Omni-directional antenna and three semi-directional antennas. This uses only as much power as necessary at each antenna. This configuration forms a star topology, which is commonly used in point-to-multipoint connections.

Question 7

You are performing an outdoor installation of an Omni-directional antenna. Which of the following will you need to do to ensure a proper installation?

Accepted Answer

You should install a lightning arrestor to protect against transient currents to ensure a proper installation procedure.
Key Takeaway: Installing lightning arrestors, sealing connectors that are outside the building, proper grounding, and lightning rods are all significant parts of an outdoor installation that should not be missed. Visual line of sight is not necessary to have a good RF connection.

Question 8

Which of the following is not a hardware or software option on a wireless bridge?

Accepted Answer

Full-duplex radio links are not a hardware or software option on a wireless bridge.
Key Takeaway: Radios can either transmit or receive on a particular frequency, but not both simultaneously; hence, all wireless LAN radios are half duplex. Full-duplex communication is not an option available on a wireless LAN. Wireless LAN radio manufacturers do not build their radios in a full duplex mode because of the very high cost associated with it.

Question 9

Which of the following statements is true about PoE devices from different manufacturers?

Accepted Answer

The statement that is true about PoE devices from different manufacturers is that they may cause damage to devices from other vendors.
Key Takeaway: Power over Ethernet, or PoE technology, describes a system to safely pass electrical power, along with data, on Ethernet cabling. Because no standard yet exists for PoE, manufacturers implement PoE in various ways. Various voltages and polarities are used, as well as different sets of unused pins in the Cat5 cable. Hence, you should always try to use both wireless LAN and PoE equipment from the same vendor. This ensures they are compatible and no electrical damage will be caused.

Question 10

A wireless LAN installation has a 50-meter cable running between access point and a highly-directional antenna. The output signal sent and received is very weak at each end of the link. Which of the following devices should you add to the configuration to fix the problem?

Accepted Answer

You should add a bi-directional amplifier to fix the problem.
Key Takeaway: Adding a bi-directional amplifier in this scenario will amplify the signal produced by the access point before the antenna transmits the signal. Although the received signal has the same amplitude, the bi-directional amplifier boosts the signal before it enters the access point so that the signal. This ensures that the signal is above the amplitude threshold of the access point.

Question 11

You are a consultant installing a wireless LAN that will connect two buildings that are 16.7 km apart. You are facing some issues with gusty winds. Which of the following antennas should you use to fix this problem?

Accepted Answer

You should use a High-gain Grid to fix this problem with gusty winds.
Key Takeaway: While both parabolic dish and grid antennas will perform the function of connecting buildings miles apart, the grid antenna is designed for maximum resistance to wind loading. This antenna is perforated to let the wind pass through.

Question 12

You need to allow outdoor users to connect to your network via a wireless LAN. Which of the following features would allow you to use an indoor access point with an outdoor antenna?

Accepted Answer

You should use detachable antennas to allow outdoor users to connect to your network via a wireless LAN.
Key Takeaway: Access points and bridges are typically mounted inside the building, unless placed in a weatherproof enclosure. It is often more economical to place access points and bridges indoors, requiring that the antenna be detachable. Mounting the antenna outdoors and running a long cable between the antenna and access point allows the administrator to protect the access point against weather and theft.

Question 13

When a station sends an RTS, the Duration/ID field notifies the other stations that they must set their NAV. Which of the following values should the stations set their NAV to?

Accepted Answer

The stations should set their NAV values to the time necessary to transmit the CTS, Data, and ACK frames.
Key Takeaway: When the RTS is sent, the value of the Duration/ID field is equal to the time necessary for the CTS, Data, and ACK frames to be transmitted. The Duration/ID field can be interpreted in two ways depending upon the frame type. In the Power-Save Poll messages, this field is the Station ID. In all other frames, this is the duration value used to calculate the NAV.

Question 14

Which of the following medium access methods supports QoS requirements under the 802.11e amendment?

Accepted Answer

Hybrid Coordination Function Controlled Access supports QoS requirements under the 802.11e amendment.
Key Takeaway: Hybrid Coordination Function Controlled Channel Access allows for CFPs to be initiated at almost any time during a CP. This kind of CFP is called a Controlled Access Phase. A CAP is initiated by the AP whenever it wants to send a frame to a station or receive a frame from a station. Hybrid Coordination Function Controlled Access is not limited to per-station queuing and can provide per-session service. It is the most advanced and complex coordination function. HCCA support is not mandatory for 802.11e APs.

Question 15

You are installing a wireless LAN in an office where the laptop computers have no USB support. Which of the following client devices should be used as a stand-alone client connection to the wireless LAN?

Accepted Answer

A PCMCIA card can be used as a stand-alone client connection to the wireless LAN.
Key Takeaway: In this case, only PCMCIA cards are stand-alone wireless LAN connectivity devices. PCMCIA, or Personal Computer Memory Card International Association, is a form factor of a peripheral interface designed for laptop computers.

Question 16

Jack has purchased a semi-directional antenna and an access point from different vendors. They have been certified as a system by the FCC through a third party. What type of cables or connectors must be used as part of this system to connect the access point to the antenna?

Accepted Answer

Jack should use an RF cable with connectors matching the access point and a pigtail cable with appropriate connectors for the antenna and RF cable connection.
Key Takeaway: A pigtail cable is used to adapt two different kinds of connectors. Typically, one of the connectors is an industry standard type, such as an N type or SMA. Having the RF cable connector match the access point connector avoids buying separate adapter connectors, which insert more loss into the circuit. The pigtail cable will be attached to the RF cable and the antenna.

Question 17

You are to provide low-cost wireless Internet access for an office with 5 sales agents. Which of the following devices should you use?

Accepted Answer

You should use a Wireless residential gateway to provide low-cost wireless Internet access for an office with 5 sales agents.
Key Takeaway: Wireless residential gateways are sometimes referred to as SOHO devices. They provide the necessary connectivity for both wired and wireless clients in a small network environment. They also provide needed upstream Internet connectivity and internal functionality such as DHCP.

Question 18

You are to recommend wireless LAN equipment that allows a corporate user to place limits on the bandwidth used by each of their wireless users. Which of the following devices would you recommend?

Accepted Answer

You should use an Enterprise wireless gateway to allow a corporate user to place limits on the bandwidth used by each of their wireless users.
Key Takeaway: Enterprise wireless gateways support role-based access control, or RBAC, where profiles can be attached to user accounts allowing specific types of access functionality. The access functionality may include rate limiting on a per-user basis.

Question 19

You are concerned about hackers intruding your wireless network. Which of the following settings should you modify on the access point to address this?

Accepted Answer

You should modify the WEP configuration on the access point to avoid hackers intruding your wireless network.
Key Takeaway: If output power is only high enough to allow company personnel to attach to the network, but not passers-by, then the network is likely more secure. Setting WEP keys and MAC filters before deployment makes a wireless network more secure.

Question 20

You are to increase the capacity of an existing wireless LAN that works on FHSS technology. You want FHSS to be replaced with the DSSS technology to achieve the objective. Which of the following statements could justify your judgment?

Accepted Answer

New FHSS devices placed in the system may not be compatible with the older devices.
Key Takeaway: Compatibility is a major concern with FHSS systems. The two standards manufacturing FHSS hardware are losing popularity. They are incompatible standards and there are very few organizations performing FHSS testing for interoperability. Hence, the system must be migrated to DSSS.

Quiz 1: Certified Wireless Network Administrator (CWNA)