Network+ N10-006 Chapter 8

You are configuring a wireless LAN (WLAN) with three wireless access points having overlapping coverage areas. The wireless access points are using the 2.4 GHz frequency band, and are located in the United States. What three non-overlapping channels in the 2.4 GHz band should you select?

1, 6, 11

What are some design goals to keep in mind when selecting an antenna?

1. Required distance between an AP and wireless client 2. Pattern of coverage area 3. Indoor/outdoor environment 4. Avoiding interference with other APs

What is the maximum bandwidth of an 802.11b wireless LAN (WLAN)?

11 Mbps

The IEEE 802.11b wireless standard has which of the following frequency band / maximum bandwidth parameters?

2.4 GHz / 11 Mbps

In a wireless LAN (WLAN) operating in the 2.4 GHz band, access points (APs) with adjacent coverage areas should have how many channels of separation to avoid interfering with one another?

5 In the 2.4 GHz band of frequencies, channels are separated by 5 MHz, with the exception of Channel 14, which has 12 MHz of separation from Channel 13. However, a single channel's transmission can spread over a frequency range of 22 MHz. As a result, channels must have five channels of separation (that is, 5 * 5 MHz = 25 MHz, which is greater than 22 MHz).

What is the IEEE 802.11a wireless standard frequency band / maximum bandwidth parameters?

5 GHz / 54 Mbps

What is the maximum bandwidth of an 802.11a wireless LAN (WLAN)?

54 Mbps

What is the maximum bandwidth of an 802.11g wireless LAN (WLAN)?

54 Mbps

What is the maximum range of the IEEE 802.11n wireless standard?

70 m indoors/ 250 m outdoors

Which wireless LAN (WLAN) standards can operate in the 5 GHz frequency band?

802.11a 802.11n

Orthogonal Frequency Division Multiplexing (OFDM) is a wireless LAN (WLAN) transmission method. What are three of the WLAN standards support OFDM?

802.11a 802.11g 802.11n Direct-Sequence Spread Spectrum (DSSS) is supported by 802.11b and 802.11g. Orthogonal Frequency Division Multiplexing (OFDM) is supported by 802.11a, 802.11g, and 802.11n. Note that 802.11g can support either OFDM or DSSS.

Direct-Sequence Spread Spectrum (DSSS) is a wireless LAN (WLAN) transmission method. Which WLAN standards support DSSS?

802.11b 802.11g

Which wireless LAN (WLAN) standards can operate in the 2.4 GHz frequency band?

802.11b 802.11n 802.11g

You are configuring a wireless access point (AP). You specify a wireless standard of 802.11n operating in the 2.4 GHz band. You also select an option to make it operate in a "backwards compatible" mode. Therefore, what additional 802.11 standards are supported?

802.11g 802.11b

What wireless technology allows the IEEE 802.11n standard to achieve higher throughput than other standards (that is, IEEE 802.11 a/b/g) by using multiple antennas for transmission and reception?

802.11n One way 802.11n achieves superior throughput is through the use of a technology called multiple input multiple output (MIMO). MIMO uses multiple antennas for transmission and reception. These antennas do not interfere with one another thanks to MIMO's use of spatial multiplexing, which encodes data based on the antenna from which the data will be transmitted. Both reliability and throughput can be increased with MIMO's simultaneous use of multiple antennas.

Which of the following approaches to wireless LAN (WLAN) security involves the use of an authentication server?

802.1X IEEE 802.1X is a technology that allows wireless clients to authenticate with an authentication server

A wireless LAN (WLAN) containing only one access point (AP) is known as what type of WLAN?

A Basic Service Set (BSS) WLAN uses a single AP. BSS WLANs are said to run in infrastructure mode (as opposed to ad hoc mode), because wireless clients connect to an AP, which is typically connected to a wired network infrastructure

What is Service Set Identifier (SSID)?

Can be thought of as the name of a WLAN. Often, an AP will broadcast the name of a WLAN's SSID, thus allowing wireless devices to see that the WLAN is available.

What is Extended Service Set (ESS) WLAN?

Containing two or more APs. Like a BSS WLAN, ESS WLANs operate in infrastructure mode.

A wireless LAN (WLAN) containing at least two access points (APs) is known as what type of WLAN?

ESS An Extended Service Set (ESS) WLAN is a WLAN containing two or more APs. Like a BSS WLAN, ESS WLANs operate in infrastructure mode.

A wireless LAN (WLAN) configured to work in an ad hoc fashion (that is, without requiring the use of an access point) is known as what type of WLAN?

IBSS An Independent Basic Service Set (IBSS) WLAN can be created without the use of an access point (AP). This type of ad hoc WLAN can be useful for temporary connections between wireless devices. For example, you might temporarily interconnect two laptop computers to transfer a few files.

Which of the following approaches to wireless LAN (WLAN) security restricts access to a WLAN based on a computer's wireless interface card?

MAC address filtering An AP can be configured with a listing of MAC addresses that are permitted to associate with the AP. If a malicious user attempts to connect via their laptop (whose MAC address is not on the list of trusted MAC addresses), that user is denied access. One drawback to "MAC address filtering" is the administrative overhead required to keep an approved list of MAC addresses up-to-date. Another issue with MAC address filtering is a knowledgeable user could falsify the MAC address of their wireless network card, making their device appear to be an approved device.

What is a common reason for disabling SSID broadcast in a wireless LAN (WLAN)?

To better conceal the SSID of a WLAN.

What is Basic Service Set (BSS)?

Uses a single AP. BSS WLANs are said to run in infrastructure mode (as opposed to ad hoc mode), because wireless clients connect to an AP, which is typically connected to a wired network infrastructure

Which of the approache to wireless LAN (WLAN) security uses RC4 as its encryption algorithm?

WEP A WLAN using Wired Equivalent Privacy (WEP) has an AP configured with a static WEP key. Wireless clients needing to associate with an AP are configured with an identical key (making this a pre-shared key (PSK) approach to security). Also, WEP uses RC4 as its encryption algorithm

What are two of the common wireless security standards?

WPA WEP

Which of the following wireless LAN (WLAN) security threats involves performing reconnaissance to identify open wireless access points (APs) that could potentially become targets of future attacks?

War driving

What type of antenna radiates power at relatively equal power levels in all directions?

omnidirectional

Which of the following approaches to wireless LAN (WLAN) security uses TKIP for encryption?

WPA

Which approache to wireless LAN (WLAN) security requires users to authenticate against an authentication server's database, rather than a client being configured with a PSK?

WPA Enterprise

Which approaches to wireless LAN (WLAN) security uses AES for encryption?

WPA2

If multiple wireless access points exist in a wireless LAN (WLAN), what percentage of coverage overlap should the access points have?

10 to 15 percent A WLAN with multiple access points should be setup such that users can roam from one access point's coverage area to another access point's coverage area, without losing connectivity. Therefore, a design best practice for WLANs is to have 10 - 15 percent overlap in coverage areas.

What type of cordless phone is most likely to interfere with a wireless LAN (WLAN)?

2.4 GHz 802.11b and 802.11g WLANs operate in the 2.4 GHz band. Additionally, many 802.11n also operate in the 2.4 GHz band (while some 802.11n networks operate in the 5 GHz band). As a result, 2.4 GHz cordless phones can interfere with WLANs operating in that same band of frequencies.

The IEEE 802.11n wireless standard has which frequency band / maximum bandwidth parameters?

2.4 GHz or 5 GHz / > 300 Mbps The 802.11n standard can operate using the 2.4 GHz frequency band or the 5 GHz frequency band, or both. The theoretical maximum bandwidth of 802.11n exceeds 300 Mbps.

What is the maximum range of the IEEE 802.11b wireless standard?

32 m indoors / 140 m outdoors

What is the maximum range of the IEEE 802.11g wireless standard?

32 m indoors / 140 m outdoors

In a wireless LAN (WLAN), what might cause a"multipath" problem?

metal file cabinet In electromagnetic theory, radio waves cannot propagate through a perfect conductor. So, while metal filing cabinets and large appliances are not perfect conductors, they are sufficient to cause degradation of a WLAN signal. For example, a WLAN signal might hit a large air conditioning unit, causing the radio waves to be reflected and scattered in multiple directions. Not only does this limit the range of the WLAN signal, but radio waves carrying data might travel over different paths. This multipath issue can cause data corruption.

What is the wireless LAN (WLAN) security threats known as an "evil twin?"

rogue access point A malicious user could set up their own access point to which legitimate users would connect. Such an AP is called a rogue access point. That malicious user could then use a packet sniffer to eavesdrop on communication flowing through their access point. To cause unsuspecting users to connect to the rogue access point, the malicious user could configure the rogue access point with the same Service Set Identifier (SSID) used by a legitimate AP. When a rogue access point is configured with the SSID of legitimate AP, the rogue access point is commonly referred to as an "evil twin."