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Question 1

What is the purpose of the OSI physical layer?

Answer 1

transmitting bits across the local media

Question 2

Why are two strands of fiber used for a single fiber optic connection?

Answer 2

They allow for full-duplex connectivity.

Question 3

Which characteristic describes crosstalk?

Answer 3

the distortion of the transmitted messages from signals carried in adjacent wires

Question 4

Which procedure is used to reduce the effect of crosstalk in copper cables?

Answer 4

twisting opposing circuit wire pairs together

Question 5

A network administrator is measuring the transfer of bits across the company backbone for a mission critical financial application. The administrator notices that the network throughput appears lower than the bandwidth expected. Which three factors could influence the differences in throughput? (Choose three.)

Answer 5

the amount of traffic that is currently crossing the network
the type of traffic that is crossing the network
the latency that is created by the number of network devices that the data is crossing

Question 6

What are two characteristics of fiber-optic cable? (Choose two.)

Answer 6

It is not affected by EMI or RFI.
It is more expensive than UTP cabling is.

Question 7

. What is a primary role of the Physical layer in transmitting data on the network?

Answer 7

create the signals that represent the bits in each frame on to the media
Explanation: The OSI physical layer provides the means to transport the bits that make up a frame across the network media. This layer accepts a complete frame from the data link layer and encodes it as a series of signals that are transmitted to the local media.

Question 8

With the use of unshielded twisted-pair copper wire in a network, what causes crosstalk within the cable pairs?

Answer 8

the magnetic field around the adjacent pairs of wire
Crosstalk is a type of noise, or interference that occurs when signal transmission on one wire interferes with another wire. When current flows through a wire a magnetic field is produced. The produced magnetic field will interface the signal carried in the adjacent wire.

Question 9

In addition to the cable length, what two factors could interfere with the communication carried over UTP cables? (Choose two.)

Answer 9

Electromagnetic interference (EMI) or radio frequency interference (RFI) – EMI and RFI signals can distort and corrupt the data signals being carried by copper media.
Crosstalk – Crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire interfering with the signal in an adjacent wire.

Question 10

Which two devices commonly affect wireless networks? (Choose two.)

Answer 10

cordless phones
microwaves

Question 11

Which two statements describe the services provided by the data link layer? (Choose two.)

Answer 11

It manages the access of frames to the network media.
It packages various Layer 3 PDUs into a frame format that is compatible with the network interface.
Explanation: The data link layer is divided into two sub layers, namely Logical Link Control (LLC) and Media Access Control (MAC). LLC forms a frame from the network layer PDU into a format that conforms to the requirements of the network interface and media. A network layer PDU might be for IPv4 or IPv6. The MAC sub layer defines the media access processes performed by the hardware. It manages the frame access to the network media according to the physical signaling requirements (copper cable, fiber optic, wireless, etc.)

Question 12

What is the function of the CRC value that is found in the FCS field of a frame?

Answer 12

to verify the integrity of the received frame

Question 13

What is contained in the trailer of a data-link frame?

Answer 13

error detection

Question 14

Which statement describes a characteristic of the frame header fields of the data link layer?

Answer 14

They vary depending on protocols.

Question 15

A network team is comparing physical WAN topologies for connecting remote sites to a headquarters building. Which topology provides high availability and connects some, but not all, remote sites?

Answer 15

partial mesh
Explanation: Partial mesh topologies provide high availability by interconnecting multiple remote sites, but do not require a connection between all remote sites. A mesh topology requires point-to-point links with every system being connected to every other system. A point-to-point topology is where each device is connected to one other device. A hub and spoke uses a central device in a star topology that connects to other point-to-point devices.

Question 16

Which two fields or features does Ethernet examine to determine if a received frame is passed to the data link layer or discarded by the NIC? (Choose two.)

Answer 16

Frame Check Sequence
minimum frame size
Explanation: An Ethernet frame is not processed and is discarded if it is smaller than the minimum (64 bytes) or if the calculated frame check sequence (FCS) value does not match the received FCS value. Auto-MDIX (automatic medium-dependent interface crossover) is Layer 1 technology that detects cable straight-through or crossover types. The source MAC address is not used to determine how the frame is received. CEF (Cisco Express Forwarding) is a technology used to expedite Layer 3 switching.

Question 17

Which media communication type does not require media arbitration in the data link layer?

Answer 17

full-duplex
Explanation: Half-duplex communication occurs when both devices can both transmit and receive on the medium but cannot do so simultaneously. Full-duplex communication occurs when both devices can transmit and receive on the medium at the same time and therefore does not require media arbitration. Half-duplex communication is typically contention-based, whereas controlled (deterministic) access is applied in technologies where devices take turns to access the medium.

Question 18

Which statement describes an extended star topology?

Answer 18

End devices connect to a central intermediate device, which in turn connects to other central intermediate devices.

Question 19

What is a characteristic of the LLC sublayer?

Answer 19

It places information in the frame allowing multiple Layer 3 protocols to use the same network interface and media.
Explanation: The Logical Link Control (LLC) defines the software processes that provide services to the network layer protocols. The information is placed by LLC in the frame and identifies which network layer protocol is being used for the frame. This information allows multiple Layer 3 protocols, such as IPv4 and IPv6, to utilize the same network interface and media.

Question 20

What are three ways that media access control is used in networking? (Choose three.)

Answer 20

Ethernet utilizes CSMA/CD.
Media access control provides placement of data frames onto the media.
Data link layer protocols define the rules for access to different media.
Explanation: Wired Ethernet networks use CSMA/CD for media access control. IEEE 802.11 wireless networks use CSMA/CA, a similar method. Media access control defines the way data frames get placed on the media. The controlled access method is deterministic, not a contention-based access to networks. Because each device has its own time to use the medium, controlled access networks such as legacy Token Ring do not have collisions.

Question 21

During the encapsulation process, what occurs at the data link layer for a PC connected to an Ethernet network?

Answer 21

The physical address is added.
Explanation: The Ethernet frame includes the source and destination physical address. The trailer includes a CRC value in the Frame Check Sequence field to allow the receiving device to determine if the frame has been changed (has errors) during the transmission.

Question 22

What three items are contained in an Ethernet header and trailer? (Choose three.)

Answer 22

source MAC address
destination MAC address
error-checking information
Explanation: Layer 2 headers contain the following:

Frame start and stop indicator flags at the beginning and end of a frame
Addressing – for Ethernet networks this part of the header contains source and destination MAC addresses
Type field to indicate what Layer 3 protocol is being used
Error detection to determine if the frame arrived without error

Question 23

What type of communication rule would best describe CSMA/CD?

Answer 23

access method
Explanation: Carrier sense multiple access collision detection (CSMA/CD) is the access method used with Ethernet. The access method rule of communication dictates how a network device is able to place a signal on the carrier. CSMA/CD dictates those rules on an Ethernet network and CSMA/CA dictates those rules on an 802.11 wireless LAN.

Question 24

Which three basic parts are common to all frame types supported by the data link layer? (Choose three.)

Answer 24

Header
Data
Trailer

Question 25

Which statement is true about the CSMA/CD access method that is used in Ethernet?

Answer 25

All network devices must listen before transmitting.
Explanation: Legacy bus-topology Ethernet LAN uses CSMA/CD as network media access control protocol. It works by detecting a collision in the medium and backing off (after transmitting a jam signal) as necessary. When one host wants to transmit a frame, it listens on the medium to check if the medium is busy. After it senses that no one else is transmitting, the host starts transmitting the frame, it also monitors the current level to detect a collision. If it detects a collision, it transmits a special jam signal so that all other hosts can know there was a collision. The other host will receive this jam signal and stop transmitting. After this, both hosts enter an exponential backoff phase and retry transmission.

Question 26

What is the auto-MDIX feature on a switch?

Answer 26

the automatic configuration of an interface for a straight-through or a crossover Ethernet cable connection

Question 27

Refer to the exhibit. What is the destination MAC address of the Ethernet frame as it leaves the web server if the final destination is PC1?

Answer 27

00-60-2F-3A-07-CC
Explanation: The destination MAC address is used for local delivery of Ethernet frames. The MAC (Layer 2) address changes at each network segment along the path. As the frame leaves the web server, it will be delivered by using the MAC address of the default gateway.

Question 28

A Layer 2 switch is used to switch incoming frames from a 1000BASE-T port to a port connected to a 100Base-T network. Which method of memory buffering would work best for this task?

Answer 28

shared memory buffering
Explanation: With shared memory buffering, the number of frames stored in the buffer is restricted only by the of the entire memory buffer and not limited to a single port buffer. This permits larger frames to be transmitted with fewer dropped frames. This is important to asymmetric switching, which applies to this scenario, where frames are being exchanged between ports of different rates. With port-based memory buffering, frames are stored in queues that are linked to specific incoming and outgoing ports making it possible for a single frame to delay the transmission of all the frames in memory because of a busy destination port. Level 1 cache is memory used in a CPU. Fixed configuration refers to the port arrangement in switch hardware.

Question 29

What are two examples of the cut-through switching method? (Choose two.)

Answer 29

fast-forward switching
fragment-free switching
Explanation: Store-and forward switching accepts the entire frame and performs error checking using CRC before forwarding the frame. Store-and-forward is often required for QOS analysis. Fast-forward and fragment-free are both variations of the cut-through switching method where only part of the frame is received before the switch begins to forward it.

Question 30

Which frame forwarding method receives the entire frame and performs a CRC check to detect errors before forwarding the frame?

Answer 30

store-and-forward switching

Question 31

What is the purpose of the FCS field in a frame?

Answer 31

to determine if errors occurred in the transmission and reception
Explanation: The FCS field in a frame is used to detect any errors in the transmission and receipt of a frame. This is done by comparing the CRC value within the frame against a computed CRC value of the frame. If the two values do not match, then the frame is discarded.

Question 32

Which switching method has the lowest level of latency?

Answer 32

fast-forward
Explanation: Fast-forward switching begins to forward a frame after reading the destination MAC address, resulting in the lowest latency. Fragment-free reads the first 64 bytes before forwarding. Store-and-forward has the highest latency because it reads the entire frame before beginning to forward it. Both fragment-free and fast-forward are types of cut-through switching.

Question 33

A network administrator is connecting two modern switches using a straight-through cable. The switches are new and have never been configured. Which three statements are correct about the final result of the connection? (Choose three.)

Answer 33

The link between the switches will work at the fastest speed that is supported by both switches.
The link between switches will work as full-duplex.
The auto-MDIX feature will configure the interfaces eliminating the need for a crossover cable.
Explanation: Modern switches can negotiate to work in full-duplex mode if both switches are capable. They will negotiate to work using the fastest possible speed and the auto-MDIX feature is enabled by default, so a cable change is not needed.

Question 34

Which advantage does the store-and-forward switching method have compared with the cut-through switching method?

Answer 34

frame error checking
Explanation: A switch using the store-and-forward switching method performs an error check on an incoming frame by comparing the FCS value against its own FCS calculations after the entire frame is received. In comparison, a switch using the cut-through switching method makes quick forwarding decisions and starts the forwarding process without waiting for the entire frame to be received. Thus a switch using cut-through switching may send invalid frames to the network. The performance of store-and-forward switching is slower compared to cut-through switching performance. Collision detection is monitored by the sending device. Store-and-forward switching does not use IPv4 Layer 3 and 4 information for its forwarding decisions

Question 35

When the store-and-forward method of switching is in use, what part of the Ethernet frame is used to perform an error check?

Answer 35

CRC in the trailer
Explanation: The cyclic redundancy check (CRC) part of the trailer is used to determine if the frame has been modified during transit.​ If the integrity of the frame is verified, the frame is forwarded. If the integrity of the frame cannot be verified, then the frame is dropped.

Question 36

Which switching method uses the CRC value in a frame?

Answer 36

store-and-forward

Question 37

What are two actions performed by a Cisco switch? (Choose two.)

Answer 37

using the source MAC addresses of frames to build and maintain a MAC address table
utilizing the MAC address table to forward frames via the destination MAC address
Explanation: Important actions that a switch performs are as follows:

When a frame comes in, the switch examines the Layer 2 source address to build and maintain the Layer 2 MAC address table.
It examines the Layer 2 destination address to determine how to forward the frame. When the destination address is in the MAC address table, then the frame is sent out a particular port. When the address is unknown, the frame is sent to all ports that have devices connected to that network.

Question 38

Which two statements describe features or functions of the logical link control sublayer in Ethernet standards? (Choose two.)

Answer 38

Logical link control is implemented in software.
The data link layer uses LLC to communicate with the upper layers of the protocol suite.
Explanation: Logical link control is implemented in software and enables the data link layer to communicate with the upper layers of the protocol suite. Logical link control is specified in the IEEE 802.2 standard. IEEE 802.3 is a suite of standards that define the different Ethernet types. The MAC (Media Access Control) sublayer is responsible for the placement and retrieval of frames on and off the media. The MAC sublayer is also responsible for adding a header and a trailer to the network layer protocol data unit (PDU).

Question 39

What is the auto-MDIX feature?

Answer 39

It enables a device to automatically configure an interface to use a straight-through or a crossover cable.
Explanation: The auto-MDIX feature allows the device to configure its network port according to the cable type that is used (straight-through or crossover) and the type of device that is connected to that port. When a port of a switch is configured with auto-MDIX, this switch can be connected to another switch by the use of either a straight-through cable or a crossover cable.

Question 40

What is one advantage of using the cut-through switching method instead of the store-and-forward switching method?

Answer 40

has a lower latency appropriate for high-performance computing applications
Explanation: Cut-through switching provides lower latency switching for high-performance computing (HPC) applications. Cut-through switching allows more invalid frames to cross the network than store-and-forward switching. The cut-through switching method can make a forwarding decision as soon as it looks up the destination MAC address of the frame.​

Question 41

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?​

Answer 41

Explanation: A straight-through cable is commonly used to interconnect a host to a switch and a switch to a router. A crossover cable is used to interconnect similar devices together like switch to a switch, a host to a host, or a router to a router. If a switch has the MDIX capability, a crossover could be used to connect the switch to the router; however, that option is not available. A rollover cable is used to connect to a router or switch console port.

Question 42

Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.

Answer 42

Explanation: Issuing the command ipconfig /all from the PC0 command prompt displays the IPv4 address and MAC address. When the IPv4 address 10.1.1.5 is pinged from PC0, the switch stores the source MAC address (from PC0) along with the port to which PC0 is connected. When the destination reply is received, the switch takes the destination MAC address and compares to MAC addresses stored in the MAC address table. Issuing the show mac-address-table on the PC0 Terminal application displays two dynamic MAC address entries. The MAC address and port entry that does not belong to PC0 must be the MAC address and port of the destination with the IPv4 address 10.1.1.5.

Question 43

What does the term “attenuation” mean in data communication?

Answer 43

loss of signal strength as distance increases

Question 44

What makes fiber preferable to copper cabling for interconnecting buildings? (Choose three.)

Answer 44

greater distances per cable run
limited susceptibility to EMI/RFI
greater bandwidth potential

Question 45

What OSI physical layer term describes the process by which one wave modifies another wave?

Answer 45

modulation

Question 46

What OSI physical layer term describes the capacity at which a medium can carry data?

Answer 46

bandwidth

Question 47

What OSI physical layer term describes the measure of the transfer of bits across a medium over a given period of time?

Answer 47

throughput

Question 48

What OSI physical layer term describes the amount of time, including delays, for data to travel from one point to another?

Answer 48

latency

Question 49

What OSI physical layer term describes the measure of usable data transferred over a given period of time?

Answer 49

goodput

Question 50

What OSI physical layer term describes the physical medium for microwave transmissions?

Answer 50

air

Question 51

Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)

Answer 51

Controls the NIC responsible for sending and receiving data on the physical medium.
Implements a trailer to detect transmission errors.
Case 2:

Provides synchronization between source and target nodes.
Integrates various physical technologies.~
Case 3:
Provides synchronization between source and target nodes.
Implements a trailer to detect transmission errors.
Case 4:
Integrates various physical technologies.
Provides synchronization between source and target nodes.
Case 5:
Integrates various physical technologies.
Controls the NIC responsible for sending and receiving data on the physical medium.
Case 6:

Controls the NIC responsible for sending and receiving data on the physical medium
Provides a mechanism to allow multiple devices to communicate over a shared medium.

Question 52

Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)

Answer 52

Enables IPv4 and IPv6 to utilize the same network interface and media.
Places information in the frame that identifies which network layer protocol is being used for the frame.

Question 53

Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)

Answer 53

Adds Layer 2 control information to network protocol data.
Places information in the frame that identifies which network layer protocol is being used for the frame.

Question 54

Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)

Answer 54

Adds Layer 2 control information to network protocol data.
Enables IPv4 and IPv6 to utilize the same network interface and media.

Question 55

Which two functions are performed at the LLC sublayer of the OSI data link layer? (Choose two.)

Answer 55

Enables IPv4 and IPv6 to utilize the same network interface and media.
Adds Layer 2 control information to network protocol data.

Question 56

What action will occur if a switch receives a frame with the destination MAC address FF:FF:FF:FF:FF:FF?

Answer 56

The switch forwards it out all ports except the ingress port.

Question 57

What action will occur if a switch receives a frame with the destination MAC address 01:00:5E:00:00:D9?

Answer 57

The switch forwards it out all ports except the ingress port.

Question 58

What action will occur if a host receives a frame with a destination MAC address of FF:FF:FF:FF:FF:FF?

Answer 58

The host will process the frame.

Question 59

What action will occur if a switch receives a frame and does have the source MAC address in the MAC table?

Answer 59

The switch refreshes the timer on that entry.

Question 60

What action will occur if a host receives a frame with a destination MAC address it does not recognize?

Answer 60

The host will discard the frame.

Question 61

Which type of UTP cable is used to connect a PC to a switch port?

Answer 61

straight-through