CCNA 1 v7.0 Modules 4 - 7: Ethernet Concepts Exam

What is the purpose of the OSI physical layer?

transmitting bits across the local media*

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

They allow for full-duplex connectivity.*

Which characteristic describes crosstalk?

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

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

twisting opposing circuit wire pairs together*

Match the situation with the appropriate use of network media.

* copper cables - horizontal cabling structure / desktop PCs in an enterprise office

*fiber optic - backbone cabling in an enterprise / long-haul networks

*wireless - guest access in a coffee shop / waiting rooms in a hospital

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?

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

What are two characteristics of fiber-optic cable?

It is not affected by EMI or RFI(crosstalk) / It is more expensive than UTP cabling is

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

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.

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

the magnetic field around the adjacent pairs of wire

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

crosstalk / electromagnetic interference

Which two devices commonly affect wireless networks?

cordless phones / microwaves

Which two statements describe the services provided by the data link layer?

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

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

to verify the integrity of the received frame

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

error detection

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

They vary depending on protocols.

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?

partial mesh

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?

Frame Check Sequence / minimum frame size

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

full-duplex

Which statement describes an extended star topology?

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

What is a characteristic of the LLC sublayer?

It places information in the frame allowing multiple Layer 3 protocols to use the same network interface and media.*

What are three ways that media access control is used in networking?

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

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

The physical address is added.

What three items are contained in an Ethernet header and trailer?

source MAC address / destination MAC address / error-checking information

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

access method

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

header / data / trailer

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

All network devices must listen before transmitting

What is the auto-MDIX feature on a switch?

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

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?

shared memory buffering

What are two examples of the cut-through switching method

fast-forward switching / fragment-free switching

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

store-and-forward switching

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

to determine if errors occured in the transmission and reception

Which switching method has the lowest level of latency?

fast-forward

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?

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.*

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

frame error checking

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

CRC in the trailer

Which switching method uses the CRC value in a frame?

store-and-forward

What are two actions performed by a Cisco switch?

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

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

Logical link control is implemented in software. / The data link layer uses LLC to communicate with the upper layers of the protocol suite.

What is the auto-MDIX feature?

It enables a device to automatically configure an interface to use a straight-through or a crossover cable.*

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

has a lower latency appropriate for high-performance computing applications

Which is a multicast MAC address?

01-00-5E-00-00-03

What does the term "attenuation" mean in data communication?

loss of signal strength as distance increases*

What makes fiber preferable to copper cabling for interconnecting buildings?

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

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

modulation

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

bandwidth

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

throughput

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

latency

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

goodput

What OSI physical layer term describes the physical medium which uses electrical pulses?

copper cable

What OSI physical layer term describes the physical medium that uses the propagation of light?

fiber-optic cable

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

air

Which two functions are performed at the MAC sublayer of the OSI data link layer?

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

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

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.

Which two functions are performed at the MAC sublayer of the OSI data link layer?

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

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

The switch refreshes the timer on that entry.

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

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

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

The host will discard the frame