CCNA1 Modules 4-7 Exam

Question 1

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?

Answer 1

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

Answers Explanation & Hints:
Throughput usually does not match the specified bandwidth of physical links due to multiple factors. These factors include, the amount of traffic, type of traffic, and latency created by the network devices the data has to cross.

Question 2

What are two characteristics of fiber-optic cable?

Answer 2

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

Answers Explanation & Hints:
Fiber-optic cabling supports higher bandwidth than UTP for longer distances. Fiber is immune to EMI and RFI, but costs more, requires more skill to install, and requires more safety precautions.

Question 3

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

Answer 3

create the signals that represent the bits in each frame on to the media

Answers Explanation & Hints:
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 4

Read answer

Answer 4

Answers Explanation & Hints:

Copper Cables – horizontal cabling structure and desktop PCs in offices in an enterprise

Fiber optic – backbone cabling in an enterprise and long-haul networks

Wireless – coffee shops and waiting rooms in a hospital

Question 5

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

Answer 5

the magnetic field around the adjacent pairs of wire

Answers Explanation & Hints:
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 6

Read answer

Answer 6

Answers Explanation & Hints:

Network cabling include different types of cables:
UTP cable consists of four pairs of color-coded wires that have been twisted together and then encased in a flexible plastic sheath.

STP cable uses four pairs of wires, each wrapped in a foil shield, which are then wrapped in an overall metallic braid or foil.

Coaxial cable uses a copper conductor and a layer of flexible plastic insulation surrounds the copper conductor.

Fiber cable is a flexible, extremely thin, transparent strand of glass surrounded by plastic insulation.

Question 7

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

Answer 7

crosstalk
electromagnetic interference

Answers Explanation & Hints:

Copper media is widely used in network communications. However, copper media is limited by distance and signal interference. Data is transmitted on copper cables as electrical pulses. The electrical pulses are susceptible to interference from two sources:

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 8

Read answer

Answer 8

Answers Explanation & Hints:

Network cabling include different types of cables:
UTP cable consists of four pairs of color-coded wires that have been twisted together and then encased in a flexible plastic sheath.

STP cable uses four pairs of wires, each wrapped in a foil shield, which are then wrapped in an overall metallic braid or foil.
Coaxial cable uses a copper conductor and a layer of flexible plastic insulation surrounds the copper conductor.

Fiber cable is a flexible, extremely thin, transparent strand of glass surrounded by plastic insulation.

Question 9

Which two devices commonly affect wireless networks?

Answer 9

cordless phones
microwaves

Answers Explanation & Hints:

Radio Frequency Interference (RFI) is the interference that is caused by radio transmitters and other devices that are transmitting in the same frequency.

Question 10

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

Answer 10

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.

Answers Explanation & Hints:

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 11

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

Answer 11

to verify the integrity of the received frame

Answers Explanation & Hints:

The CRC value in the FCS field of the received frame is compared to the computed CRC value of that frame, in order to verify the integrity of the frame. If the two values do not match, then the frame is discarded.

Question 12

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

Answer 12

error detection

Answers Explanation & Hints:

The trailer in a data-link frame contains error detection information that is pertinent to the frame included in the FCS field. The header contains control information, such as the addressing, while the area that is indicated by the word “data” includes the data, transport layer PDU, and the IP header.

Question 13

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

Answer 13

They vary depending on protocols

Answers Explanation & Hints:

All data link layer protocols encapsulate the Layer 3 PDU within the data field of the frame. However, the structure of the frame and the fields that are contained in the header vary according to the protocol. Different data link layer protocols may use different fields, like priority/quality of service, logical connection control, physical link control, flow control, and congestion control.

Question 14

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 14

partial mesh

Answers Explanation & Hints:

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 15

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?

Answer 15

Frame Check Sequence
minimum frame size

Answers Explanation & Hints:

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 16

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

Answer 16

full-duplex

Answers Explanation & Hints:

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 17

Which statement describes an extended star topology?

Answer 17

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

Answers Explanation & Hints:

In an extended star topology, central intermediate devices interconnect other star topologies.

Question 18

What is a characteristic of the LLC sublayer?

Answer 18

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

Answers Explanation & Hints:

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 19

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

Answer 19

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.

Answers Explanation & Hints:
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 20

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

Answer 20

The physical address is added.

Answers Explanation & Hints:

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 21

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

Answer 21

source MAC address

destination MAC address

error-checking information

Answers Explanation & Hints:

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 22

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

Answer 22

access method

Answers Explanation & Hints:

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 23

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

Answer 23

header

data

trailer

Answers Explanation & Hints:

The data link protocol is responsible for NIC-to-NIC communications within the same network. Although there are many different data link layer protocols that describe data link layer frames, each frame type has three basic parts:
Header
Data
Trailer

Question 24

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

Answer 24

All network devices must listen before transmitting.

Answers Explanation & Hints:

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 25

What is the auto-MDIX feature on a switch?

Answer 25

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

Answers Explanation & Hints:

The auto-MDIX enables a switch to use a crossover or a straight-through Ethernet cable to connect to a device regardless of the device on the other end of the connection.

Question 26

Read answer

Answer 26

Answers Explanation & Hints:

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 27

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 27

shared memory buffering

Answers Explanation & Hints:

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 28

What are two examples of the cut-through switching method?

Answer 28

fast-forward switching

fragment-free switching

Answers Explanation & Hints:

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 29

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

Answer 29

store-and-forward switching

Answers Explanation & Hints:

Fast-forward and fragment-free switching are variations of cut-through switching, which begins to forward the frame before the entire frame is received.

Question 30

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

Answer 30

to determine if errors occurred in the transmission and reception

Answers Explanation & Hints:

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 31

Which switching method has the lowest level of latency?

Answer 31

fast-forward

Answers Explanation & Hints:
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 32

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?

Answer 32

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.

Answers Explanation & Hints:
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 33

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

Answer 33

frame error checking

Answers Explanation & Hints:
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 34

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 34

CRC in the trailer

Answers Explanation & Hints:
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 35

Which switching method uses the CRC value in a frame?

Answer 35

store-and-forward

Answers Explanation & Hints:
When the store-and-forward switching method is used, the switch receives the complete frame before forwarding it on to the destination. The cyclic redundancy check (CRC) part of the trailer is used to determine if the frame has been modified during transit.​​ In contrast, a cut-through switch forwards the frame once the destination Layer 2 address is read. Two types of cut-through switching methods are fast-forward and fragment-free.

Question 36

What are two actions performed by a Cisco switch?

Answer 36

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

Answers Explanation & Hints:
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 37

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

Answer 37

Logical link control is implemented in software.

The data link layer uses LLC to communicate with the upper layers of the protocol suite.

Answers Explanation & Hints:
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 38

What is the auto-MDIX feature?

Answer 38

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

Answers Explanation & Hints:
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 39

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

Answer 39

has a lower latency appropriate for high-performance computing applications​

Answers Explanation & Hints:
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 40

Which is a multicast MAC address?

Answer 40

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

Answers Explanation & Hints:
Multicast MAC addresses begin with the special value of 01-00-5E.

Question 41

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

Answer 41

loss of signal strength as distance increases

Answers Explanation & Hints:
Data is transmitted on copper cables as electrical pulses. A detector in the network interface of a destination device must receive a signal that can be successfully decoded to match the signal sent. However, the farther the signal travels, the more it deteriorates. This is referred to as signal attenuation.

Question 42

What makes fiber preferable to copper cabling for interconnecting buildings?

Answer 42

greater distances per cable run

limited susceptibility to EMI/RFI

greater bandwidth potential

Answers Explanation & Hints:
Optical fiber cable transmits data over longer distances and at higher bandwidths than any other networking media. Unlike copper wires, fiber-optic cable can transmit signals with less attenuation and is completely immune to EMI and RFI.

Question 43

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

Answer 43

modulation

Question 44

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

Answer 44

bandwidth

Question 45

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

Answer 45

throughput

Question 46

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

Answer 46

latency

Question 47

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

Answer 47

goodput

Question 48

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

Answer 48

copper cable

Question 49

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

Answer 49

fiber-optic cable

Question 50

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

Answer 50

air

Question 51

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

Answer 51

Implements a trailer to detect transmission errors.

Controls the NIC responsible for sending and receiving data on the physical medium.

Question 52

Two functions are performed at the LLC sublayer of the OSI data link layer?

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

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

Answer 53

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.

Question 54

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

Answer 54

Controls the NIC responsible for sending and receiving data on the physical medium.

Integrates various physical technologies.

Question 55

Two functions are performed at the LLC sublayer of the OSI data link layer?

Answer 55

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 56

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

Answer 56

Provides synchronization between source and target nodes.

Integrates various physical technologies.

Question 57

Two functions are performed at the LLC sublayer of the OSI data link layer?

Answer 57

Adds Layer 2 control information to network protocol data.

Enables IPv4 and IPv6 to utilize the same network interface and media.

Question 58

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

Answer 58

Implements a trailer to detect transmission errors.

Provides synchronization between source and target nodes.

Question 59

Two functions are performed at the LLC sublayer of the OSI data link layer?

Answer 59

Enables IPv4 and IPv6 to utilize the same network interface and media.

Adds Layer 2 control information to network protocol data.

Question 60

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

Answer 60

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.

Question 61

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

Answer 61

The switch refreshes the timer on that entry.

Question 62

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

Answer 62

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

Question 63

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

Answer 63

The host will discard the frame.

Question 64

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

Answer 64

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

Question 65

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

Answer 65

The host will process the frame.

Question 66

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

Answer 66

The switch refreshes the timer on that entry.