What are two reasons for physical layer protocols to use frame encoding techniques? (Choose two)
-To reduce the number of collisions on the media.
-to distinguish data bits from control bits
-to provide better media error correction
-to identify where the frame starts and ends
-to increase the media throughput
answer
-to distinguish data bits from control bits
-to identify where the frame starts and ends
question
What is indicated by the term throughput?
answer
the measure of the bits transferred across the media over a given period of time.
question
A network administrator notices that some newly installed Ethernet cabling is carrying corrupt and distorted data signals. The new cabling was installed in the ceiling close to fluorescent lights and electrical equipment. Which two factors may interfere with the copper cabling and result in signal distortion and data corruption? (Choose two.)
-EMI
-crosstalk
-RFI
-signal attenuation
-extended length of cabling
answer
EMI
RFI
question
Which characteristic describes crosstalk?
answer
the distortion of the transmitted messages from signals carried in adjacent wires
question
What technique is used with UTP cable to help protect against signal interference from crosstalk?
answer
twisting the wires together into pairs.
question
Refer to the exhibit. The PC is connected to the console port of the switch. All the other connections are made through FastEthernet links. Which types of UTP cables can be used to connect the devices?
PC---SWITCH---ROUTER1---ROUTER2
answer
1-rollover, 2-straight-through, 3-crossover
question
Refer to the exhibit. What is wrong with the displayed termination
answer
The untwisted length of each wire is too long
question
Which type of connector does a network interface card use?
answer
RJ-45
question
What is one advantage of using fiber optic cabling rather than copper cabling?
answer
It is able to carry signals much farther than copper cabling.
question
Why are two strands of fiber used for a single fiber optic connection?
answer
They allow for full-duplex connectivity
question
A network administrator is designing the layout of new wireless network. Which 3 areas of concern should be accounted for when building a wireless network? ( Choose 3)
-mobility options
-security
-interference
-coverage area
-extensive cabling
-packet collision
answer
-security
-interference
-coverage area
question
Which layer of the OSI model is responsible for specifying the encapsulation method used for specific types of media?
answer
data link
question
What are two services performed by the data link layer of the OSI model? (choose two)
-It encrypts data packets
-it determines the path to forward packets
-it accepts layer 3 packets and encapsulates them into frames
-it provides media access control and performs error detection
-it monitors the layer 2 communication by building a MAC address table.
answer
It accepts Layer 3 packets and encapsulates them into frames
It provides medial access control and performs error detection.
question
What is true concerning physical and logical topologies?
answer
Logical topologies refer to how a network transfers data between devices
question
Which method of data transfer allows information to be sent and received at the same time?
answer
full duplex
question
Which statement describes an extended star topology?
answer
End devices connect to a central intermediate device, which in turn connects to other central intermediate devices
question
Refer to the exhibit. Which statement describes the media access control methods that are used by the networks in the exhibit?
PC(hardline)SWITCH-network1(hardline)router(lightning bolt)-network2-router2 w/antenna(wireless connection)laptop
answer
Network 1 uses CSMA/CD and Network 3 uses CSMA/CA
question
What is contained in the trailer of a data-link frame?
answer
error detection
question
As data travels on the media in a stream of 1s and 0s how does a receiving node identify the beginning and end of a frame?
answer
The transmitting node inserts start and stop bits into the frame.
question
What is the function of the CRC value that is found in the FCS field of a frame?
answer
To verify the integrity of the received frame.
question
The term _____________________ indicates the capacity of a medium to carry data and it is typically measured in kilobits per second (kb/s) or megabits per second (Mb/s)
answer
bandwidth
question
What acronym is used to reference the data link sublayer that identifies the network layer protocol encapsulated in the frame?
answer
LLC
question
multimode fiber or single mode fiber?
LED as light source
answer
multimode fiber
-LED as a light source
question
multimode fiber or single mode fiber?
Several paths of light into the fiber
answer
multimode Fiber
-Several paths of light into the fiber
question
Multimode fiber or single mode fiber?
Generally used with LANs
answer
multimode fiber
-Generally used with LANs
question
Multimode fiber or single mode fiber?
Only one ray of light into the fiber
answer
Single-mode fiber
-Only one ray of light into the fiber
question
Multimode fiber or single mode fiber?
Generally used for campus backbone
answer
Single-mode fiber
-Generally used for campus backbone
question
Multimode fiber or single mode fiber?
Laser as light source
answer
Single-mode fiber
-Laser as light source
question
What are two reasons for physical layer protocols to use frame encoding techniques? (Choose two.)
answer
To identify where the frame starts and ends
To distinguish data bits from control bits.
question
Which statement is correct about multimode fiber?
answer
SC-SC path cords are used with multimode fiber cables
question
The throughput of a FastEthernet network is 80 Mb/s. The traffic overhead for established sessions, acknowledgments, and encapsulation is 15 Mb/s for the same time period. What is the goodput for this network?
answer
65 Mb/s
question
What is the purpose of the FCS field in a frame?
answer
to determine if errors occurred in the transmission and reception
question
Which statement describes signaling at the physical layer?
answer
Sending the signals asynchronously means that they are transmitted without a clock signal.
question
What is one main characteristic of the data link layer?
answer
It shields the upper layer protocol from being aware of the physical medium to be used in the communication
question
What is one main characteristic of the data link layer?
answer
It shields the upper layer protocol from being aware of the physical medium to be used in the communication
question
10,000,000,000 b/s can also be written as...
answer
10 Gb/s
question
What are two characteristics of 802.11 wireless networks? (Choose two.)
Collisions can exist in the networks
They are collision-free networks.
They use CSMA/CD technology
Stations can transmit at any time.
They use CSMA/CA technology
answer
Collisions can exist in the networks
They see CSMA/CA technology
question
A network administrator is required to upgrade wireless access to end users in a building. To provide data rates up to 1.3 Gb/s and still be backward compatible with older devices, which wireless standard should be implemented?
answer
802.11 ac
question
How is the magnetic field cancellation effect enhanced in UTP cables?
answer
By increasing and varying the number of twists in each wire pair
question
Match the steps to the physical layer operations that occur when data is sent from one node and received at another node
What is step one?
answer
Step 1: The physical layer encodes the frames.
question
Match the steps to the physical layer operations that occur when data is sent from one node and received at another node
What is step two?
answer
The physical layer creates the signals that represent the bits in each frame.
question
Match the steps to the physical layer operations that occur when data is sent from one node and received at another node
What is step five?
answer
The physical layer restores the individual signals to their bit representations
question
Match the steps to the physical layer operations that occur when data is sent from one node and received at another node
What is step three?
answer
The signals are sent on the media one at a time.
question
Match the steps to the physical layer operations that occur when data is sent from one node and received at another node
What is step four?
answer
The physical layer retrieves the individual signals from the media.
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