George Mason University Wireless Networks Questions

QUESTION 1
1.
Select the correct statement(s) regarding network physical and logical topologies.
a. While logical topologies can be configured in star, ring, bus, and tree configurations, the
physical topology must always be in a full-mesh topology
b. logical topologies always incorporate centralized access, whereas physical topologies are
always configured as a distributed access network
c. the physical topology addresses how devices are connected, while a logical topology
addresses how devices actually communicate to one another
d. all statements are correct
10 points
QUESTION 2
1. To enable full-duplex (FDX) communications, analog signals typically incorporate time
division multiplexing (TDM) where transmit and receive data is separated by time slots.
True
False
10 points
QUESTION 3
1. What is true about the Ethernet data link layer?
a. the Ethernet data link layer is divided into two layers: MAC and LLC
b. the Ethernet data link layer defines the physical interface to the shared medium
c. the MAC address is the same as the IP address
d. all statements are correct
10 points
QUESTION 4
1. IEEE 802.3 Media Access Control Layer (MAC) is responsible for what?
a. Data encapsulation (framing, addressing, error detection)
b. Placement of frames onto the physical medium
c. Responsible for CSMA/CD process
d. All of the above
10 points
QUESTION 5
1. Select the correct statement(s) regarding client-server networks.
a. client computers have a centralized location for all shared data
b. centralized authentication and authorization can be easily implemented
c. either centralized or decentralized (distributed) access control can be implemented
d. all are correct statements
10 points
QUESTION 6
1. Select the correct statement(s) regarding peer-to-peer (P2P) networks.
a. computers on P2P networks have a centralized location for all shared data
b. there is a possibility that duplicate data files will exist on a P2P network
c. P2P networks always use centralized authentication and access methods
d. all are correct statements
10 points
QUESTION 7
1. What is the major difference between centralized and decentralized control and access?
a. data collisions can occur on either centralized or decentralized access methods
b. decentralized access methods must involve a process to handle occasional data collisions
(e.g., CSMA/CD, CSMA/CA)
c. centralized access control only works when CSMA methods are used
d. CSMA/CD is used with decentralized access, while CSMA/CA is used with centralized
access methods
10 points
QUESTION 8
1. Select the correct statement(s) regarding DCE and DTE interfaces.
a. DTE and DCE describes the device types (e.g., computers, switches, routers, etc.)
b. distinguishing between DTE and DCE is only required for half-duplex communications
c. DTE and DCE describes the interface and direction of data flow between devices; a
single device may have both types of interfaces
d. all statements are correct
10 points
QUESTION 9
1.
Select the correct statement(s) regarding shared Ethernet LANs.
a. all nodes on a shared Ethernet LAN must have the ability to read the address of all
incoming packets
b. CSMA/CD is always required on a shared Ethernet LAN
c. only guided medium is used in a shared Ethernet LAN
d. all statements are correct
10 points
QUESTION 10
1. Switched Ethernet, similar to shared Ethernet, must incorporate CSMA/CD to handle data
collisions.
True
False
10 points
QUESTION 11
1. Select the correct statement(s) regarding decentralized (distributed) access control on a
LAN.
a. no centralized access process exists, and therefore each connected station has the
responsibility for controlling its access
b. data collisions are possible, therefore mechanisms such as CDMA/CD are required
c. when a data collision occurs, the nearest station detecting the collision transmits
a jamming signal
d. all of the above are correct
10 points
QUESTION 12
1. IEEE 802.3 Ethernet is a family of specifications that only describes the data link layer.
True
False
10 points
QUESTION 13
1. Select the correct statement(s) that are associated with 100Base-T LANs.
a. supports a theoretical data rate of 100 Mbps
b. specification belongs to the IEEE 802.3 standard
c. operates over a UTP physical layer
d. all statements are correct
10 points
QUESTION 14
1.
Increasing data capacity (i.e., throughput) on an 802.3 LAN using UTP can be done by:
a. Increasing wire gauge (e.g., go from Cat5e to Cat6 or 7)
b. Adopting a line coding technique with a higher “M”
c. Enabling both transmit and receive on a single wire pair using hybrid canceller
transceiver
d. All of the above
10 points
QUESTION 15
1. What happens when a collision is detected on a shared medium Ethernet 802.3 LAN when
CSMA/CD is used?
a. The node closest to the collision sends out a jamming signal to inform all other nodes
that a collision has occurred
b. A central control node sends out a jamming signal to inform all other nodes that a
collision has occurred
c. Collisions do not occur on Ethernet LANs
d. All LAN nodes detect the collision simultaneously and each then cease any data transfer
activity
10 points
QUESTION 16
1.
Select the correct statement(s) regarding 4B5B encoding.
a. 4B5B is used to map four codeword bits into a five bit data word
b. 4B5B information bit rate is 80% of the total (information plus overhead) bit rate
c. 4B5B information bit rate is 20% of the total (information plus overhead) bit rate
d. all statements are correct
10 points
QUESTION 17
1. The IEEE 802.3 Ethernet standard describes both the physical and data link layers. As such,
each specification addresses the physical medium to be used.
True
False
10 points
QUESTION 18
1.
What is true regarding the IEEE 802.11 WLAN standard?
a. WLANs operate in the licensed operating frequencies, therefore data collisions do not
occur.
b. Since 802.11 WLANs implement DSSS and OFDM, there is no need for a collision
avoidance mechanism.
c. The 802.11 Point Coordination Function (PCF) is an optional feature that enables the
WLAN to operate as a centralized access network.
d. 802.11 networks only implement centralized access using access points (APs)
10 points
QUESTION 19
1.
Which method is used over IEEE 802.11 WLANs to limit data collisions caused by a hidden
node?
a. frame exchange protocol
b. four frame exchange protocol
c. DCF
d. CSMA/CD
10 points
QUESTION 20
1.
Select the correct statement(s) regarding the use of DSSS and OFDM on IEEE 802.11 WLANs.
a. DSSS and OFDM are more spectrally efficient than traditional FDM
b. DSSS and OFDM are both spread spectrum techniques that are easy to implement and
less complicated than traditional FDM
c. DSSS and OFDM are only used on guided IEEE 802.3 LANs
d. all statements are correct
10 points
QUESTION 21
1.
What are ways to increase data capacity on an 802.11 WLAN?
a. increase frequency bandwidth and/or operating frequency
b. Adopt MIMO to increase bit rate and help avoid multipath fading
c. implement M’ary modulation techniques
d. All of the above
10 points
QUESTION 22
1. The 802.11 Point Coordination Function (PCF) is an optional feature that enables the WLAN to
operate as a centralized access network.
True
False
10 points
QUESTION 23
1. Select the correct statement(s) regarding IEEE 802.11 medium access.
a. PCF mode requires CSMA/CA
b. PCF is an option selected by the network to support centralized medium access
c. both DCF and PCF modes require licensed frequency assignments
d. all statements are correct
10 points
QUESTION 24
1.
Wireless IEEE 802.11 LANs can use either CSMA/CD or CSMA/CA access methods; however,
CSMA/CA is preferred since it eliminates all data collisions between nodes.
True
False
10 points
QUESTION 25
1.
IEEE 802.15 Bluetooth is a standard that implements a centralized access method.
True
False
10 points
QUESTION 26
1.
Select the correct statement(s) regarding 802.15 Bluetooth piconets and scatternets.
a. A device in one piconet cannot participate as a device in another piconet at the same
time
b. A scatternet is comprised of 8 or more devices
c. A bridge device acts to interface the Bluetooth device to a LAN
d. Up to eight devices can comprise a piconet
10 points
QUESTION 27
1.
ZigBee is an 802.15.4 specification intended to be simpler to implement, and to operate at lower
data rates over unlicensed frequency bands.
True
False
10 points
QUESTION 28
1. How many 802.15 Bluetooth devices make up a piconet?
a. 6
b. 7
c. 8
d. 9