Chapter 8 Flashcards
(18 cards)
Copper cable and fiber-optic cable are examples of ____________, which is used to carry the communication signal.
physical media
What is the purpose of encoding?
A. To identify the start and stop bits in a frame
B. To denote the physical layer’s connectors of computers in relation to the way they connect to network media
C. To control the way frames are placed on the media at the data link layer
D. To represent the data bits by using different voltages, light patterns, or electromagnetic waves as they are placed onto the physical media
D. Encoding represents the data bits by using different voltages, light patterns, or electromagnetic waves as they are placed onto the physical media.
What two signaling methods use voltage to encode bits?
NRZ (nonreturn to zero) and Manchester
What best describes the purpose of the physical layer?
A. Ensures reliable transmission of data across a physical link
B. Determines connectivity and path selection between two end systems
C. Establishes the physical addressing, networking topology, and media access
D. Defines the functional specifications for links between end systems and the electrical, optical, and radio signals
D. The chief purpose of the physical layer is to define the functional specifications for links between end systems and the electrical, optical, and radio signals that carry data. Reliability, path selection, and media access are the tasks of other layers.
What is the most common UTP connector type?
RJ-45
Through what process does UTP cable help to avoid crosstalk?
A. Shielding of cable
B. Twisting of pairs
C. Grounding the endpoints
D. Cladding in cable
B. Crosstalk is reduced by the twisting of cables in the UTP (unshielded twisted-pair) cable. UTP has no cladding, shielding, or grounding points.
What is the required order of wires in a connector called?
pinout
What are the advantages of using fiber-optic cable over copper cable? (Choose three.)
A. Copper is more expensive
B. Immunity to electromagnetic interference
C. Careful cable handling
D. Longer maximum cable length
E. Efficient electrical current transfer
F. Greater bandwidth potential
B, D, F. The advantages of using fiber-optic cabling include immunity to electromagnetic interference, longer maximum cable length, greater bandwidth reception and decoding requirements, and antenna design.
The physical media most susceptible to security breaches is ____________.
wireless. Because wireless is open to anyone with a wireless receiver, it is more susceptible to security breaches than copper or fiber-optic media.
What is the purpose of cladding in fiber-optic cables?
A. Cable grounding
B. Noise cancellation
C. Prevention of light loss
D. EMI protection
C. Cladding helps prevent light loss. No other listed functions pertain to fiber-optic cable.
Which two of the following are true about straight-through cables?
A. They work in Cisco console ports.
B. They can be either 568A or 568B.
C. They can connect a host to a switch.
D. They can connect two switches.
B, C. Rollovers work in Cisco console ports, and crossovers would connect two switches.
A ____________ cable is also known as a Cisco cable because it is generally used as a connection to Cisco equipment.
rollover cable
Which of the following measures the actual data transfer rate over a medium?
A. Bandwidth
B. Output
C. Throughput
D. Goodput
C. Throughput measures actual data rates. Bandwidth is the line capacity, and goodput measures only the rate of usable application layer data bits that arrive.
Which of the following is NOT true?
A. 1 Gbps = 1,000,000,000 bits per second
B. 1 kbps = 1000 bits per second
C. 1 Mbps = 100,000 bits per second
D. 1 Tbps = 1,000,000,000,000 bits per second
C. 1 Mbps = 1,000,000 (106) bps
What is synchronization?
A. Keeping the correct time of day on all network machines
B. The timing mechanism devices use when transmitting data
C. Devices processing bits to the data link layer at the same speed
D. Constant bit times throughout the network
B. Synchronization between devices allows them to know when frames begin and end.
What is true about “bit time”?
A. It is the time it takes to encapsulate application data into a bit segment.
B. It is the time it takes for a NIC to move a bit from the data link layer to the Layer 1
media.
C. IEEE standards require it to be the same on all NICs.
D. It is the time it takes for a byte to traverse the copper or fiber cable.
B. Bit time changes depending on the speed of the NIC. The time it takes a bit to traverse the network is slot time (which counts bits, not bytes).
A user has a peer-to-peer network with two directly connected hosts. To add a third host, the user installs a hub and adds two straight-through cables so that each computer has its own connection to the hub. What will be the result of this network upgrade?
A. All three hosts will link to the hub.
B. Two hosts will link to the hub.
C. One host will link to the hub.
D. None of the hosts will link to the hub
B. The two hosts with straight-through cables will link to the hub. The third host is using the original cable, which is a crossover cable appropriate for peer-to-peer connections, but will not link to a hub from a host.
A network administrator for a small wood products manufacturing company has throughput issues in the A wing of her building. The network devices are the same for all wings, and all appear to be performing normally, but the throughput has become consistently significantly lower in the A wing. Sales orders are up, and the machines on the production floor are working to full capacity. The administrator is under pressure to get throughput up to acceptable speed. In researching the problem, she determines the following list of facts. Which three of them are most likely to be contributing factors to the poor network performance?
A. The A wing has the largest number of hosts connected to the network.
B. The janitor buffs the floor of that wing at 4:00 p.m. Wednesdays. The other wings
are buffed at night.
C. Some employees in the A wing have added refrigerators and microwave ovens close
to their workstations.
D. The A wing has had a computer network for three years; the other wings have had a
network for four years.
E. Hosts in the A wing are located next to the manufacturing shop.
F. The A wing has Cat 5 cable throughout, while the other wings have wireless and Cat 5.
A, C, E. A: The A wing, having the most connected workers, can have too much traffic on the cable and packets can be getting dropped. C: Refrigerator compressors and microwave ovens can cause interference on a network. E: Because orders are up, the wing’s proximity to the manufacturing shed could be because of electromagnetic interference from the machines on the production line.
Incorrect answers: B: The janitor’s actions are intermittent, and the network problems are consistent. D and F: These differences should provide more reliability, not less.
