Network Infrastructure: Layer 2 Ethernet Switches

Questions and Answers

What is the primary function of a layer 2 Ethernet switch?

To route data between subnets

To provide network access to wireless devices

To forward data based on MAC addresses (correct)

To translate IP addresses to DNS names

What is the length of a MAC address in bits?

32 bits

24 bits

64 bits

48 bits (correct)

What command can be used to display the physical address of a network interface card on a Windows device?

ping -l

ipconfig /all (correct)

ipconfig /dns

tracert -d

What is the purpose of an access point in a network?

To provide network access to wireless devices Signup and view all the answers

What is the representation of a MAC address?

12 hexadecimal characters Signup and view all the answers

What is the layer 2 address also known as?

Physical address Signup and view all the answers

What is the primary difference between a layer 2 switch and a router?

A layer 2 switch forwards data based on MAC addresses, while a router forwards data based on IP addresses Signup and view all the answers

What is the function of Switch 1 and Switch 2 in the network topology?

To forward data based on MAC addresses Signup and view all the answers

What is the primary function of a layer 2 switch in a network?

To connect multiple devices together and allow them to communicate Signup and view all the answers

What is the benefit of having separate collision domains in a network?

Improved network performance Signup and view all the answers

What is the purpose of ARP in a network?

To resolve IP addresses to layer 2 addresses Signup and view all the answers

What is the advantage of full duplex communication in a network?

Improved network performance Signup and view all the answers

What is the default behavior of a layer 2 switch in terms of broadcast domains?

One broadcast domain for the entire switch Signup and view all the answers

What is the purpose of a broadcast in a network?

To send data to all devices on the network Signup and view all the answers

What is the function of the backplane in a switch?

To buffer data during congestion Signup and view all the answers

What is the benefit of using a layer 2 switch over a hub in a network?

Improved network performance Signup and view all the answers

What is the primary purpose of a layer 2 switch in a network topology?

To forward frames of data based on layer 2 addresses Signup and view all the answers

What is the purpose of VLANs in a network?

To divide a switch into multiple broadcast domains Signup and view all the answers

What is the term for the address assigned by the manufacturer of a network interface card?

Burned-in address (BIA) Signup and view all the answers

What information does a layer 2 switch use to make forwarding decisions?

Destination MAC address Signup and view all the answers

What is the advantage of using unshielded twisted pair (UTP) cables in a network?

Full duplex communication Signup and view all the answers

What is the purpose of a switch building a table of layer 2 addresses and corresponding ports?

To enable efficient forwarding of frames of data Signup and view all the answers

What is the term for the address that identifies a network interface card at layer 2?

MAC address Signup and view all the answers

What is the benefit of using a layer 2 switch instead of a hub?

Improved network efficiency through targeted forwarding Signup and view all the answers

What is the term for the process of a device sending a frame of data into the network, including the source and destination layer 2 addresses?

Frame transmission Signup and view all the answers

What is the purpose of a PC performing an ARP request?

To obtain the MAC address of the default gateway Signup and view all the answers

What is the role of the switch in forwarding a frame of data from a PC to the default gateway?

To forward the frame to the correct port based on the destination MAC address Signup and view all the answers

What is the term for the address that a network interface card uses to identify itself at layer 2?

MAC address Signup and view all the answers

What is a characteristic of a switch that makes it better than a hub?

It has full duplex capabilities Signup and view all the answers

What is the number of collision domains on a 48-port switch?

48 Signup and view all the answers

What is the number of broadcast domains on a 48-port switch by default?

1 Signup and view all the answers

What is the purpose of a switch learning layer 2 addresses?

To make forwarding decisions based on layer 2 addresses Signup and view all the answers

What command can be used to show the layer 2 addresses learned by a switch?

show mac address-table Signup and view all the answers

What is the significance of a switch having full duplex capabilities?

It can send and receive data simultaneously Signup and view all the answers

What is the purpose of a switch storing layer 2 addresses in a table?

To make forwarding decisions based on layer 2 addresses Signup and view all the answers

What happens when a device sends a broadcast on a layer 2 switch?

The switch forwards the broadcast to all devices Signup and view all the answers

What is the significance of a switch having 48 ports?

It can forward data to 48 devices Signup and view all the answers

What is the purpose of a switch dynamically learning layer 2 addresses?

To make forwarding decisions based on layer 2 addresses Signup and view all the answers

What is the reason why the switch has not learned the MAC address of PC3 initially?

PC3 is very quiet in the virtualized environment Signup and view all the answers

When PC1 sends a unicast frame to its default gateway, which of the following is true?

The frame is sent only to the port that connects to the default gateway. Signup and view all the answers

What is the command used by PC3 to display the details of its ethernet adapter?

ifconfig eth0 Signup and view all the answers

What is the purpose of the ARP request sent by PC3?

To request the MAC address of the default gateway Signup and view all the answers

What happens when PC1 sends a broadcast frame into the network?

The switch sends the frame to all ports in the broadcast domain. Signup and view all the answers

Why did the ping to 172.20.5.1 not result in a broadcast?

The ARP cache already had the layer 2 information for the default gateway. Signup and view all the answers

What is the result of the switch learning the MAC address of PC3?

The switch can now forward frames to PC3 using the MAC address Signup and view all the answers

What is the purpose of an ARP request?

To request the layer 2 address of a device. Signup and view all the answers

What is the significance of each port on the switch being its own collision domain?

It allows the switch to reduce collisions on the network Signup and view all the answers

Why did the ping to 172.20.5.99 result in three broadcasts?

The ARP request was sent three times because there was no response. Signup and view all the answers

What is a significant characteristic of a layer 2 switch in terms of broadcast domains?

It combines multiple collision domains into a single broadcast domain. Signup and view all the answers

What happens when the switch receives a frame destined for a MAC address it has learned?

The switch sends the frame to the port associated with the MAC address Signup and view all the answers

What is the primary advantage of a layer 2 switch over a layer 2 bridge?

It reduces the number of collision domains. Signup and view all the answers

Why does the switch not need to send frames to every port when it receives a frame destined for a known MAC address?

Because it has learned the MAC address of the device Signup and view all the answers

What is the result of a switch receiving a frame with an unknown destination MAC address?

The switch sends the frame to all ports in the broadcast domain. Signup and view all the answers

What is an important distinction between layer 2 switching and layer 3 forwarding?

Layer 2 switching uses MAC addresses, while layer 3 forwarding uses IP addresses. Signup and view all the answers

What is the purpose of a layer 2 switch in a network?

To filter traffic based on MAC addresses. Signup and view all the answers

What is the result of capturing traffic on eth0 while sending traffic from PC3?

The capture shows both the ARP request and the ping traffic Signup and view all the answers

What is the result of a device sending a frame with a broadcast destination MAC address?

The switch sends the frame to all ports in the broadcast domain. Signup and view all the answers

What is the role of a layer 2 switch in a network with multiple routers?

It performs layer 2 switching between devices and routers. Signup and view all the answers

Why does the switch learn the MAC address of PC3 when it sends traffic?

Because PC3 sends traffic with its source MAC address Signup and view all the answers

What is a key advantage of using multiple collision domains in a network?

It reduces the number of collisions on the network. Signup and view all the answers

Why did the ping to 172.20.5.50 result in a successful response?

The IP address belonged to another device on the network. Signup and view all the answers

What is true about the devices connected to the switch?

They are part of the same broadcast domain Signup and view all the answers

What happens when a device sends a unicast frame to a MAC address that is not in the switch's MAC address table?

The switch floods the frame to all ports except the one that received it. Signup and view all the answers

What is the primary difference between a layer 2 switch and a layer 2 bridge?

A layer 2 switch provides multiple collision domains, while a layer 2 bridge provides a single collision domain. Signup and view all the answers

What is the effect of a broadcast sent from a device connected to a layer 2 switch?

It is sent to all active ports on the switch. Signup and view all the answers

What is the relationship between layer 2 switching and the forwarding of data between routers?

Layer 2 switching occurs between devices, while forwarding between routers occurs at layer 3. Signup and view all the answers

What is a layer 2 bridge commonly used for?

To connect two segments of a network, creating a single collision domain. Signup and view all the answers

What is the primary benefit of full-duplex communication on a layer 2 switch?

It enables every device to send and receive at the same time. Signup and view all the answers

Study Notes

Layer 2 Switches

A Layer 2 switch makes forwarding decisions based on Layer 2 addresses, specifically Media Access Control (MAC) addresses.
A MAC address is 48 bits long, represented by 12 hexadecimal characters, each representing 4 bits.
Each network interface card (NIC) has a unique MAC address.

Learning MAC Addresses

A Layer 2 switch builds a table of MAC addresses associated with each port.
The switch learns MAC addresses by looking at the source MAC address of incoming frames.
When a device sends a frame, the switch updates its table with the MAC address and the port it is connected to.

Forwarding Decisions

When a switch receives a frame, it checks the destination MAC address and forwards it to the port associated with that MAC address.
If the switch doesn't know the MAC address, it forwards the frame to all ports (flooding).
A switch can operate in full duplex, allowing devices to send and receive frames simultaneously.

Collision Domains and Broadcast Domains

Each port on a switch is its own collision domain, reducing collisions and increasing network efficiency.
A switch has one broadcast domain, meaning a broadcast frame is sent to all ports.

ARP Requests

An ARP (Address Resolution Protocol) request is a broadcast frame sent to resolve an IP address to a MAC address.
The switch forwards ARP requests to all ports in the broadcast domain.
The device responding to the ARP request sends a unicast frame with its MAC address, which the switch learns and updates its table.

Switch Configuration and Demonstration

A show mac address-table command can be used to display the switch's MAC address table.
The switch can be configured to capture packets and display the MAC address table to demonstrate learning and forwarding decisions.
A Layer 2 switch with 48 ports would have 48 collision domains and one broadcast domain.### Ping and ARP Request
When a ping is sent, it sends an ARP request as a broadcast to find the layer 2 address of the device with the specified IP address
The ARP request is sent to all devices on the same broadcast domain, including PC2 and PC3
If the IP address is not found, the ping will fail and an ARP request will be sent again

Layer 2 Switching

A layer 2 switch is a single broadcast domain, where all devices receive broadcast messages
A layer 2 switch forwards broadcast messages to all active ports
A layer 2 switch improves upon a layer 2 bridge by giving every device its own collision domain on its own port
This allows every device connected to a layer 2 switch to send and receive at the same time, making it full duplex on every port

Layer 2 Bridge

A layer 2 bridge is a stepping stone to layer 2 switching, with only a couple of ports
A layer 2 bridge divides a single collision domain into multiple collision domains, one for each port

Layer 2 Forwarding

Layer 2 forwarding occurs between devices, such as between a PC and a switch, and between switches
Layer 2 switching happens between routers, where switches forward data based on layer 2 addresses
Layer 2 forwarding is what happens between routers, where switches make forwarding decisions based on layer 2 addresses

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Description

This quiz covers the basics of layer 2 Ethernet switches, their role in network infrastructure, and their functionality. It explores the topology of switches and their connections to servers and computers.