Chapter 4: Ethernet Basics

Question 1

Ethernet hubs take an incoming packet and ________ it out to the other connected ports.

Answer 1

repeat

Question 2

What is appended to the beginning of the Ethernet frame?

Answer 2

Preamble

Question 3

Which networking devices can use the Spanning Tree Protocol (STP)?

Answer 3

Switches

Question 4

What device directs packets based on MAC address?

Answer 4

Switch

Question 5

What is the IEEE committee that controls Ethernet standards called?

Answer 5

802.3

Question 6

What topology does Ethernet use?

Answer 6

Star bus

Question 7

What is Ethernet?

Answer 7

A standard for a family of network technologies that share the same basic bus topology, frame type. and network access method.

Question 8

What is the purpose of a preamble on a frame?

Answer 8

It gives a receiving NIC time to realize a frame is coming and to know exactly where the frame starts.

Question 9

What does the type field of an Ethernet frame do?

Answer 9

Helps the receiving computer interpret the frame contents at a very basic level. (IPv4 or IPv6)

Question 10

What is the minimum size of an Ethernet frame?

Answer 10

64 bytes

Question 11

What happens if an Ethernet frame has fewer than 64 bytes of data?

Answer 11

The sending NIC will automatically add extra data (padding)

Question 12

What is CSMA/CD?

Answer 12

Ethernet networks use a system called carrier sense multiple access/collision detection (CSMA/CD) to determine which computer should use a shared cable at any given moment.

Question 13

What is a collision domain?

Answer 13

A group of nodes (NICs/computers) that have the capability of sending frames at the same time as each other resulting in collisions.

Question 14

What do the nodes do if a collision occurs?

Answer 14

Each node stops transmitting, determines a random time to wait, then retransmits.

Question 15

What is the average maximum percentage of collisions in an Ethernet network?

Answer 15

10 percent

Question 16

What is the central box for 10BaseT?

Answer 16

A hub

Question 17

Which pins of an RJ-45 connector are used to send data? receive data?

Answer 17

Pins 1 and 2 are used to send data

Pins 3 and 6 are used to receive data

Question 18

What does it mean for a NIC to run in half-duplex mode?

Answer 18

The NIC can only communicate in one direction at a time, i.e. cannot send while receiving and vice versa.

Question 19

What does it mean for a NIC to run in full-duplex mode?

Answer 19

The NIC can send and receive at the same time.

Question 20

What is the arrangement of wires according to the TIA/EIA 568A standard?

Answer 20

WG G WO B WB O WBr Br

Question 21

What is the arrangement of wires according to the TIA/EIA 568B standard?

Answer 21

WO O WG B WB G WBr Br

Question 22

Fill in the following qualities of 10BaseT

1) Speed:
2) Signal Type:
3) Distance:
4) Node Limit:
5) Topology:
6) Cable Type:
7) Connector:

Answer 22

1) 10 Mbps
2) Baseband
3) 100m between hub and node
4) 1024/hub
5) Star bus
6) CAT3 or better UTP
7) RJ-45

Question 23

Fill in the following qualities of 10BaseFL:

1) Speed:
2) Signal Type:
3) Distance:
4) Node Limit:
5) Topology:
6) Cable Type:
7) Connector:

Answer 23

1) 10Mbps
2) Baseband
3) 2000m between hub and node
4) 1024/hub
5) Star bus
6) Multimode fiber
7) ST or SC

Question 24

What is a media dependent interface?

Answer 24

A regular old port on a hub or switch.

Question 25

What is a media dependent interface crossover (MDIX)?

Answer 25

An uplink port on a hub.

Question 26

What is a coupler?

Answer 26

A connection device used to extend an Ethernet segment

Question 27

What are the two ways you can connect hubs?

Answer 27

1) Uplink ports | 2) Crossover cables

Question 28

What kind of cable do you use for connecting hubs using uplink ports?

Answer 28

Straight-through (both ends the same wire arrangement)

Question 29

Where do you insert the cable ends when connecting hubs using uplink ports?

Answer 29

One end of the cable in the uplink port of one hub and the end to any regular port on the other hub.

Question 30

What is a crossover cable?

Answer 30

A UTP cable that has one end arranged according to TIA/EIA 568A and the other according to TIA/EIA 568B.

Question 31

Where do you insert the cable ends when connecting hubs with crossover cables?

Answer 31

Each end is plugged into a regular port.

Question 32

What is a bridge?

Answer 32

A bridge acts like a repeater or hub to connect two Ethernet networks, and filters and forwards traffic between those segments based on the MAC addresses of the computers on those segments.

Question 33

What does it mean to filter traffic?

Answer 33

Stop it from crossing from one network to the next.

Question 34

What does it mean to forward traffic?

Answer 34

Pass traffic originating on one side of the bridge to the other.

Question 35

What is the advantage of switches over hubs?

Answer 35

A switch effectively creates point-to-point connections between two conversing computers, so every conversation between two computers gets the full bandwidth.

Question 36

A switch stores copies of the MAC addresses of each connected computer in a table called a ___________.

Answer 36

Source Address Table (SAT)

Question 37

Why can two nodes connected to a switch send data at the same time?

Answer 37

Each port on a switch is in its own collision domain.

Question 38

What is a bridging loop?

Answer 38

A redundant connection between switches

Question 39

What is Spanning Tree Protocol (STP)?

Answer 39

STP allows switches to detect loops and set the looped port's state to blocking

Question 40

What is the frame called that STP-enabled switches use to communicate with each other?

Answer 40

Bridge Protocol Data Unit (BPDU)

Question 41

What is the stable state of a switch referred to as?

Answer 41

Convergence

Question 42

What are the steps for troubleshooting a basic hub/switch?

Answer 42

1) Check for obvious physical damage 2) Check for link lights, and try a different port if necessary 3) Check for cable damage 4) In the end, replace it