CHAPTER 12

When you are using the 2.4 GHz band for multiple access points in a WLAN in the United States, which nonoverlapping channels should you select?

1/6/11

When extending the range for a 2.4GHz WLAN, you can use nonoverlapping channels for adjacent coverage cells. However, there should be some overlap in coverage between those cells (using non-overlapping channels) to prevent a connection from dropping as a user roam from one coverage cell to another. What percentage of coverage overlap is recommended for these adjacent cells?

10% to 15%

802.11ax (WiFi 6)

2.4, 5, and 6 GHz, 9.6 Gbps (MU-MIMO). Newest wireless connection.

Which IEEE 802.11 variant supports a maximum speed of 54Mbps and uses the 2.4GHz band?

802.11g

Independent Basic Service Set (IBSS)

A WLAN can be created without the use of an AP. Such a configuration is said to work in an ad-hoc fashion. An ad hoc WLAN is useful for temporary connections between wireless devices. For example, you might temporarily interconnect two laptop computers to transfer a few files.

roaming

A feature in modern WLANs that permit users to move throughout an organization without losing WiFi access as they transition to different WiFi cells and equipment.

Multiple Input Multiple Output (MIMO)

A method that uses multiple antennas, increasing the number of signals for increased bandwidth.

channel bonding

A process in which two wireless bands are logically bonded together, forming a band with twice the bandwidth of an individual band. Some literature calls channel bonding 40MHz mode, which refers to the bonding of two adjacent 20MHz bands into a 40MHz band.

Temporal Key Integrity Protocol (TKIP)

A security protocol used in the IEEE 802.11 wireless networking standard. It was designed by the IEEE 802.11i task group and the Wi-Fi Alliance as an interim solution to replace WEP without requiring the replacement of legacy hardware. Makes it possible to use dynamic keys, which are generated on a per-packet basis.

802.11n

A standard ratified in 2009, supports a variety of speeds, depending on the implementation. Many ______ devices on the market have speed ratings in the 130Mbps-150Mbps range.

Service Set Identifier (SSID)

A string of characters that identify a WLAN. Aps participating in the same WLAN can be configured with identical SSIDs. An SSID shared among multiple APs is called an extended service set identifier (ESSID).

unidirectional antenna

A style of WiFi antenna that directs the signal in a specific direction.

Advanced Encryption Standard (AES)

A symmetrical block ciphers implemented in hardware and software that protects sensitive or confidential data through encryption.

Code Division Multiple Access (CDMA)

A technology that allows several transmitters to send information simultaneously over a single communication channel so that several users can share a band of frequencies. ___________ is used as the access method in many mobile phone standards.

omnidirectional antenna

An antenna that radiates its signal out horizontally in all directions equally.

WiFi Protected Access (WPA)

An enhancement of 802.11 encryption that secures WiFi communications. The current standard is WPA2.

wireless channel

An indication of how the WiFi frequency bands are divided up in order to carry the WiFi signal. Countries apply their own regulations to the available channels to allow users and maximum power levels within these frequency ranges.

If a WLAN does not need a user to give credentials to associate with a wireless AP and access the WLAN, what type of authentication is in use? A WEP B SSID C Open D IV

C. Open

What technology do WiFi devices use to decide when they gain access to the wireless media?

CSMA/CA

WPA/2-Personal

For checking integrity checking and advanced encryption standard (AES) for encryption.

Which security technique uses wireless technologies to create an invisible boundary around some point?

Geofencing

A WLAN formed directly between wireless clients (without the use of a wireless AP) is referred to as what type of WLAN?

IBSS

WEP's RC4 approach to encryption uses a 24-bit string of characters added to transmitted data, such that the same plain-text data frame will never appear as the same WEP-encrypted data frame. What is this string of characters called?

Initialization vector

Which of the following does IEEE 802.11n use to achieve high throughput using multiple antennas for transmission and reception?

MIMO

4G

Most popularly implemented as Long Term Evolution (LTE), a wireless data standard with theoretical download speeds of 300 Mbps and upload speeds of 75 Mbps.

Multiuser MIMO (MU-MIMO)

Technology for wireless communication that relies on multiple users or terminals, each radioing over one or more antennas to communicate with one another.

5G

The fifth-generation wireless broadband technology based on the 802.11ac standard engineered to greatly increase the speed and responsiveness of wireless networks

wireless band

The specific frequencies that are capable of carrying modern WiFi. The IEEE 802.11 uses various frequencies bands, including the 2.4 GHz, 5GHz, 6GHz, and 60GHz bands.

3G

Third generation wireless communication technology allows high speed wireless data transfer

Extended Service Set (ESS)

WLANs containing more than one AP. Like BSS WLANs, ____ WLANs operate in infrastructure mode. When you have more than one AP, take care to prevent one AP from interfering with another. Specifically, nonoverlapping channels (that is, channels 1, 6, and 11 for the 2.4-GHz band) should be selected for adjacent wireless coverage areas.

Basic Service Set (BSS)

WLANs that have just one AP are called _____ WLANs. _____ WLANs are said to run in infrastructure mode because wireless clients connect to an AP, which is typically connected to a wired network infrastructure. A _____ network is often used in residential and SOHO locations, where the signal strength provided by a single AP is sufficient to service all of the WLAN's wireless clients.

WPA-2 Enterprise

WPA configurations are used in organizations that feature stronger security mechanisms than the personal configurations available.

Which standard was developed by the WiFi Alliance implements the requirements of IEEE 802.11i?

WPA2

802.11b

Wireless networking standard that operates in the 2.4-GHz band with a theoretical maximum throughput of 11 Mbps.

802.11g

Wireless networking standard that operates in the 2.4-GHz band with a theoretical maximum throughput of 54 Mbps and is backward compatible with 802.11b.

802.11ac

Wireless networking standard that operates in the 5-GHz band and uses multiple in/multiple out (MIMO) and multi-user MIMO (MU-MIMO) to achieve a theoretical maximum throughput of 1 Gbps.

802.11a

Wireless networking standard that operates in the 5-GHz band with a theoretical maximum throughput of 54 Mbps.

What type of antenna, used in wireless APs and wireless routers in SOHO locations, radiates power equally in all directions?

omnidirectional