CCNA 1 v7 Modules 4 - 7: Ethernet Concepts

Questions and Answers

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. Signup and view all the answers

Which three factors could influence the differences in throughput in a network? (Choose three.)

The latency created by the number of network devices. Signup and view all the answers

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

It is more expensive than UTP cabling. Signup and view all the answers

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 onto the media. Signup and view all the answers

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. Signup and view all the answers

What type of cabling is shown in the graphic?

Fiber. Signup and view all the answers

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

Electromagnetic interference Signup and view all the answers

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

Cordless phones, microwaves. Signup and view all the answers

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

It manages the access of frames to the network media. Signup and view all the answers

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. Signup and view all the answers

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

Error detection. Signup and view all the answers

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

They vary depending on protocols. Signup and view all the answers

Which topology provides high availability and connects some, but not all, remote sites?

Partial mesh. Signup and view all the answers

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.)

Minimum frame size Signup and view all the answers

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

Full-duplex. Signup and view all the answers

Which statement describes an extended star topology?

End devices connect to a central intermediate device, which connects to other central intermediate devices. Signup and view all the answers

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. Signup and view all the answers

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

Ethernet utilizes CSMA/CD. Signup and view all the answers

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

The physical address is added. Signup and view all the answers

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

Destination MAC address Signup and view all the answers

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

Access method. Signup and view all the answers

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

Trailer Signup and view all the answers

Is it true that all network devices must listen before transmitting?

True Signup and view all the answers

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

00-60-2F-3A-07-CC. Signup and view all the answers

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. Signup and view all the answers

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

Fragment-free switching Signup and view all the answers

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

Store-and-forward switching. Signup and view all the answers

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

To determine if errors occurred in the transmission and reception. Signup and view all the answers

Which switching method has the lowest level of latency?

Fast-forward. Signup and view all the answers

When connecting two switches using a straight-through cable, which three statements are correct about the final result of the connection? (Choose three.)

The link will work as full-duplex. Signup and view all the answers

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

Frame error checking. Signup and view all the answers

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. Signup and view all the answers

Which switching method uses the CRC value in a frame?

Store-and-forward. Signup and view all the answers

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

Using the source MAC addresses of frames to build and maintain a MAC address table. Signup and view all the answers

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

Logical link control is implemented in software. Signup and view all the answers

What is the auto-MDIX feature?

It enables a device to automatically configure an interface to use a straight-through or a crossover cable. Signup and view all the answers

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. Signup and view all the answers

Which is a multicast MAC address?

01-00-5E-00-00-03. Signup and view all the answers

What is wrong with the displayed termination?

The untwisted length of each wire is too long. Signup and view all the answers

Which types of UTP cables can be used to connect the devices? (Select the correct options.)

Crossover Signup and view all the answers

Which port does Switch0 use to send frames to the host with the IPv4 address 10.1.1.5?

Fa0/11. Signup and view all the answers

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

Loss of signal strength as distance increases. Signup and view all the answers

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

Limited susceptibility to EMI/RFI. Signup and view all the answers

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

Modulation. Signup and view all the answers

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

Bandwidth. Signup and view all the answers

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

Throughput. Signup and view all the answers

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

Latency. Signup and view all the answers

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

Goodput. Signup and view all the answers

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

Copper cable. Signup and view all the answers

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

Fiber-optic cable. Signup and view all the answers

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

Air. Signup and view all the answers

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

Controls the NIC responsible for sending and receiving data on the physical medium. Signup and view all the answers

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

Places information in the frame that identifies which network layer protocol is being used for the frame. Signup and view all the answers

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. Signup and view all the answers

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

The host will process the frame. Signup and view all the answers

What action will occur if a switch receives a frame and does not have the source MAC address in the MAC table?

The switch refreshes the timer on that entry. Signup and view all the answers

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

Straight-through. Signup and view all the answers

Study Notes

OSI Physical Layer

Responsible for transmitting bits across local media.
Modulation: process where one wave modifies another wave.
Bandwidth: capacity of a medium to carry data.
Throughput: measure of bit transfer over a medium in a given timeframe.
Latency: time taken for data to travel from one point to another.
Goodput: measure of usable data transferred over a specific period.
Copper cable: uses electrical pulses as the physical medium.
Fiber-optic cable: uses light propagation as the physical medium.
Microwave transmissions utilize air as the physical medium.

Fiber Optic and Copper Cables

Fiber optic connections typically use two strands for full-duplex connectivity.
Fiber-optic cables are immune to electromagnetic interference (EMI) and radio frequency interference (RFI) but are more costly than unshielded twisted pair (UTP) cables.
Advantages of fiber: longer distances, less EMI/RFI susceptibility, higher bandwidth potential.

Crosstalk and Interference

Crosstalk occurs due to distortion from adjacent wire signals, often mitigated by twisting wire pairs.
UTP communication can be disrupted by crosstalk and electromagnetic interference, affecting data transmission quality.

Data Link Layer Functions

Manages frame access to network media and packages Layer 3 protocol data units (PDUs) into frame format.
Frame Check Sequence (FCS) in the trailer is used to detect errors in frame transmission.
Variables in header fields can change depending on the protocol used.

Network Topologies

Partial mesh topology connects some remote sites to a headquarters while providing high availability.
In an extended star topology, end devices connect to a central intermediate device, which connects to other such devices.

Ethernet Frame and Switching Methods

Ethernet examines the Frame Check Sequence and minimum frame size to determine frame validity.
Full-duplex communication does not require media arbitration, allowing simultaneous data transmission.
Store-and-forward switching checks the entire frame and performs a CRC to verify integrity.
Cut-through switching, including fast-forward and fragment-free methods, minimizes latency.
Shared memory buffering is ideal for switching between differing network speeds (e.g., between 1000BASE-T and 100BASE-T).

MAC Sublayer Actions

The MAC sublayer manages the Network Interface Card (NIC), placing a trailer in frames for error detection.
The Logical Link Control (LLC) sublayer allows multiple Layer 3 protocols to utilize the same network media by identifying the appropriate protocol in the frame.

Switch Operations

When a frame’s destination MAC is broadcasted (FF:FF:FF:FF:FF:FF), the switch forwards it to all ports except the one it was received on.
Multicast frames (e.g., 01:00:5E:00:00:D9) also follow the same forwarding principle.
If a switch receives a frame from a known source MAC, it refreshes that entry in its MAC address table.

UTP Cable Types

Straight-through cables are required to connect PCs to switch ports.
Various cable types, including rollover, straight-through, and crossover, serve different connection purposes, particularly in switching configurations.

Key Factors Affecting Network Throughput

Throughput can be influenced by current network traffic, types of traffic, and the latency introduced by devices the data crosses.

Error Checking in Ethernet

A frame's trailer contains error detection information crucial for maintaining data integrity during transmission.

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Description

Test your knowledge on Ethernet concepts from CCNA 1 v7 with this flashcard quiz. Focused on the OSI model and fiber optic technology, this quiz includes key definitions and principles of networking. Prepare effectively for your CCNA certification exam by mastering these concepts.