M7Q33: WLANs & Wireless Installation

Question 1

What is the original wireless standard for LANs?

A. 802.11
B. 802.3
C. 802.1
D. 802.11g

Answer 1

A. 802.11

Explanation: The original wireless standard is 802.11. From 802.11 the extensions such as 802.11a,g,n, etc were created.

Question 2

The traditional mode for wireless access where devices communicate through a wireless access point to access the LAN is called _______________.

A. Ad Hoc mode
B. BSSID mode
C. Infrastructure Mode
D. ESSID mode

Answer 2

C. Infrastructure mode

Explanation: Infrastructure mode is the “traditional” way of connecting devices to a wireless network. When in infrastructure mode a wireless device is able to scan for SSIDs and connect to wireless LANs via wireless access point. Ad Hoc mode is when devices connect directly to each other via their local wireless NICs. When network devices are in Ad Hoc mode it can cause problems if the user or installer
does not understand what Ad Hoc mode is because Ad Hoc wireless does not connect a device in the “traditional” way or directly to the company LAN. In normal circumstances Ad Hoc mode is not used.

Question 3

The concept of an ESSID is when you have multiple wireless access points that are participating in the same SSID and the clients are able to roam between different wireless access points without losing their connection to the SSID.

A. True
B. False

Answer 3

A. True

Explanation: ESSID (Extended SSID) is common in corporate networks where multiple wireless access points span across and throughout entire buildings. ESSID is the concept in which many wireless access points are all acting as part of a single system and are able to all participate in the same SSID (usually
through a wireless controller) allowing wireless clients to roam from AP to AP without losing their connection to the wireless network. BSSID (Basic SSID) on the other hand is when a single SSID is broadcasted by a single access point and other access points do not participate in the same wireless system. BSSID is what is available on basic home and SOHO wireless routers.

Question 4

The following 802.11 wireless standard extensions are capable of both 2.4GHz and 5GHz frequency bands.

(choose all that apply)

A. 802.11a
B. 802.11b
C. 802.11g
D. 802.11n
E. 802.11ac

Answer 4

D. (802.11n)

Explanation: Only 802.11n supports both the 2.4 GHz and 5 GHz frequency bands. 802.11 a and 802.11 ac are 5Ghz only, while 802.11 b/g are 2.4 GHz only.

Question 5

In 2.4 GHz wireless networks the channels 1, 6 and 11 should be used to avoid channel overlap with other access points providing the best performance.

A. True
B. False

Answer 5

A. True

Explanation: Channel 1, 6, and 11 allow for placement of access points without overlapping each other. When channels overlap such as placing a WAP on channel 1 next to another WAP on channel 1 it causes interference and the wireless clients will have trouble communicating efficiently with the wireless access points.

Question 6

MIMO (Multiple Input, Multiple Output) is a technology for using multiple antennas to transmit and receive. MIMO combined with multiple antennas provides for higher bandwidth capabilities on wireless access points. Which versions of 802.11 support MIMO?

(choose all that apply)

A. 802.11a
B. 802.11n
C. 802.11g
D. 802.11ac
E. 802.11b

Answer 6

B. (802.11n), D. (802.11ac)

Explanation: 802.11n and 802.11ac are the only 802.11 extensions that support MIMO. Under 802.11n MIMO supports up to 4 antennas (spatial streams) and under 802.11ac MIMO supports up to 8 antennas (spatial streams). It’s also important to understand the channel bandwidth for each of the standards. 802.11n has a 40 MHz maximum channel bandwidth. 802.11ac includes a minimum of 80 MHz channel bandwidth with a single antenna providing a bandwidth of 433 Mbps. The maximum channel bandwidth in 802.11ac is 160 MHz.

Question 7

For performance reasons, it’s always better to use a wireless connection even when a wired Ethernet connection is available for use.

A. True
B. False

Answer 7

B. False

Explanation: Wired Ethernet is always better than a wireless connection. At times it can seem like the two are equivalent in performance, but when tested one can always see that a wired connection provides better and more consistent performance. Now, other than the fact that wireless will have higher latency than wireless, there is one specific reason why wired will always be better than wireless and that is because wireless is only half duplex. This means that a wireless connection can only transmit or receive at any given time, but not both at the same time. Wired Ethernet connections run at full duplex meaning they can both transmit and receive at the same time. Important devices should always be
connected via a wired connection.