Wireless Questions Flashcards
Question 1
Which wireless LAN design ensures that a mobile wireless user will not lose connectivity when moving from one access point to another on the WLAN?
A. Utilizing MAC address filtering to allow the client MAC address to authenticate with the surrounding APs
B. Using adapters and access points manufactured by the same company
C. Overlapping the wireless cell coverage by at least 10%
D. Configuring all access points to use the same channel
Answer: C
Explanation
By using more than one Access Point (AP) we can create overlapping cells to allow roaming in a larger area. But we have to ensure that two APs must have at least 10% coverage overlap and they use non-overlapping channels.
Question 2
You need to troubleshoot an interference issue with the wireless LAN. Which two devices can interfere with the operation of this network because they operate on similar frequencies? (Choose two)
A. Microwave oven
B. AM radio
C. Toaster
D. Copier
E. Cordless phone
F. IP phone
G. Ipod
Answer: A E
Explanation
Microwave oven and cordless phone radiate energy in the 2.4 GHz unlicensed band so they can interfere with some WLAN standards. As the result of that, you can’t hear clearly on the phone or can’t surf web.
Question 3
Which of the following data network would you implement if you wanted a wireless network that had a relatively high data rate, but was limited to very short distances?
A. Broadband personal comm. Service (PCS)
B. Broadband circuit
C. Infrared
D. Spread spectrum
E. Cable
Answer: C
Explanation
Infrared typically requires a line-of-sight (your TV remote control, for example) which means that it is limited to very short distances. I am not sure if it is considered “relative high data rate” but infrared can transfer up to 4Mpbs.
Question 4
You need to add a wireless access point to a new office. Which additional configuration step is necessary in order to connect to an access point that has SSID broadcasting disabled?
A. Configure open authentication on the AP and the client
B. Set the SSID value in the client software to public
C. Set the SSID value on the client to the SSID configured on the AP
D. Configure MAC address filtering to permit the client to connect to the AP
Answer: C
Explanation
Service Set Identifier (SSID) is the term to identify a WLAN. In most cases SSID is broadcast by the AP, the user only needs to select that SSID and provides a correct password to access it. But in some cases for security reason, the SSID can be disabled. Users can only access to that network if they type both SSID and password correctly.
Question 5
You need to secure a new access point on the a wireless network. Which two practices help secure the configuration utilities on wireless access points from unauthorized access? (Choose two)
A. Changing the default SSID value
B. Configuring traffic filtering
C. Changing the mixed mode setting to single mode
D. Configuring a new administrator password
E. Assigning a private IP address to the AP
Answer: A D
Explanation
To improve security, you should change the default SSID value on your AP. For example, Linksys routers (which are produced by Cisco) typically have an SSID of “linksys” -> A is correct.
In an AP we can configure traffic filtering but it is mainly used for filtering which services clients can use, IP ranges, ports, websites, time access… It has no effect on securing your AP -> B is not correct.
“Mixed mode” here means we can configure AP to allow clients to use different standard like 802.11b, g or n. But setting it to single mode doesn’t have any security protection on it -> C is not correct.
We should also change the administrator password because everyone can access to the admin page of an AP by open a web browser and type the IP address of that AP (for example: http://192.168.1.1). Typically, Linksys Wireless routers have a default username/password of “admin/admin” or “admin/[blank]” which are easily guessed or found out -> D is correct.
We can access the AP by using a private IP address (in the same private network of the AP – 192.168.1.1, for example) -> E is not correct.
Question 6
You need to determine the proper security settings on a new WLAN-capable office. Which encryption type would WPA2 use in this office?
A. PSK
B. AES-CCMP
C. PPK via IV
D. TKIP/MIC
E. None of the other alternatives apply
Answer: B
Explanation
Advanced Encryption Standard (AES) is the cipher system used by RSN. It is the equivalent of the RC4 algorithm used by WPA. However the encryption mechanism is much more complex and does not suffer from the problems associated with WEP. AES is a block cipher, operating on blocks of data 128bits long.
CCMP is the security protocol used by AES. It is the equivalent of TKIP in WPA. CCMP computes a Message Integrity Check (MIC) using the well known, and proven, Cipher Block Chaining Message Authentication Code (CBC-MAC) method. Changing even one bit in a message produces a totally different result.
The AES-CCMP encryption algorithm used in the 802.11i (WPA2) security protocol. It uses the AES block cipher, but restricts the key length to 128 bits. AES-CCMP incorporates two sophisticated cryptographic techniques (counter mode and CBC-MAC) and adapts them to Ethernet frames to provide a robust security protocol between the mobile client and the access point.
Question 7
What is one reason why WPA encryption is preferred over WEP in this network?
A. The WPA key values remain the same until the client configuration is changed.
B. The values of WPA keys can change dynamically while the system is used.
C. The access point and the client are manually configured with different WPA key values.
D. A WPA key is longer and requires more special characters than the WEP key.
E. None of the other alternatives apply
Answer: B
Explanation
Wireless Encryption Protocol (WEP) uses RC4 encryption and a static 64-bit key so it can be easily broken as only 40-bits are encrypted and 24 bits are clear-text IV(Initialization Vector). It was later upgraded to 128-bit, but the IV was still clear text meaning it took slightly longer (minutes) to break-in.
WPA was introduced in 2003 as a replacement for WEP. WPA uses Temporal Key Integrity Protocol (TKIP) to automatically change the keys. TKIP still uses RC4; it just improves how it’s done
Question 8
In an effort to increase security within the wireless network, WPA is being utilized. Which two statements shown below best describe the wireless security standard that is defined by WPA? (Choose two)
A. It requires use of an open authentication method
B. It specifies use of a static encryption key that must be changed frequently to enhance security
C. It includes authentication by PSK
D. It specifies the use of dynamic encryption keys that change each time a client establishes a connection
E. It requires that all access points and wireless devices use the same encryption key
F. WPA works only with Cisc0 access points
Answer: C D
Question 9
You need to configure a new wireless access point for your network. What are three basic parameters to configure an AP? (Choose three)
A. Authentication method
B. RTS/CTS
C. RF channel
D. SSID
Answer: A C D
Explanation
Below lists basic parameters to configure an AP
