Day 2 - CSMA / CD, Switching, and VLANs Flashcards

1
Q

What is CSMA/CD?

A

Carrier Sense Multiple Access with Collision Detection

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2
Q

What does Carrier Sense mean?

A

That the wire is listened to in order to determine whether there is a signal passing along it.

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3
Q

What does Multiple Access mean?

A

More than one device is using the cables on the segment.

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4
Q

What is Collision Detection?

A

An algorithm used by a protocol to determine whether frames on the wire have become damaged due to hitting another frame.

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5
Q

Do switches reduce or increase the amount of collision domains?

A

Switches increase the number of collision domains.

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6
Q

If four PCs are connected to a switch how many collision domains are there?

A

Four.

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7
Q

Do switches or routers separate Broadcast domains?

A

Routers.

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8
Q

Do hubs reduce or increase the amount of collision domains?

A

Neither. Hubs extend the collision domain they are a part of.

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9
Q

What are the commands to adjust the speed on an interface?

A

interface [interface name]

speed [10,100,auto]

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10
Q

Do switches switch packets, frames or segments?

A

Frames.

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11
Q

What type of frame is switched out of all interfaces but the one on which they were received?

A

Broadcast and frames without a known destination (not in the MAC table).

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12
Q

What are the three main actions a switch must perform to function?

A

Forwarding or filtering (dropping) frames based on destination MAC addresses

Learning MAC addresses from incoming frames

Using STP to prevent Layer 2 loops

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13
Q

Any delay in passing traffic is know as ?

A

latency.

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14
Q

What are the three ways Cisco switches can switch traffic and which way is the default on modern switches?

A

Cut-through

Store-and-forward (default)

Fragment-free

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15
Q

What are the pros and cons of Cut-through switching?

A

Fastest switching method/lowest latency

No error checking

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16
Q

What are the pros and cons of Store-and-forward switching?

A

Error checking via CRC

Highest latency

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17
Q

What are the pros and cons of Fragment-free switching?

A

Quick and reliable

Only checks the first 64 bytes of a frame so any errors after that will be forwarded

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18
Q

What is CRC error checking?

A

Cyclic Redundancy Check

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19
Q

What is the minimum size of an Ethernet frame?

A

64 bytes

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20
Q

Fragment-free switching is also know as ?

A

runt-free switching

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21
Q

Hubs are also know as ?

A

multiport repeaters

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22
Q

Do hubs store MAC addresses?

A

no

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23
Q

The memory chip contained in a switch is know as a ?

A

application specific integrated circuit (ASIC)

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24
Q

Where is the switch table listing devices and ports stored?

A

Content Addressable Memory (CAM)

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25
Q

What is the switch command to display the CAM table?

A

show mac-address-table

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26
Q

What does OUI stand for?

A

Organizationally Unique Identifier

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27
Q

A MAC address is made up of how many bits and are they hex or binary?

A

48 binary bits

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28
Q

A MAC address is made up of a OUI of 24 binary bits and a ? of ? bits?

A

Vendor’s Number

24 binary bits

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29
Q

Name the seven components of the IEEE 802.3 Ethernet frame

A
Preamble
Start-of-frame delimiter (SFD)
Destination address
Source address
Length
Data
Frame-check sequence
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30
Q

What is the Preamble in an Ethernet frame?

A

synchronises and alerts the network card for the incoming data

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31
Q

What is the SFD in an Ethernet frame?

A

Start-of-frame delimiter, it indicates the start of the frame

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32
Q

What are the three different types of Destination MAC addresses?

A

Unicast
Broadcast
Multicast

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33
Q

What does the Length in an Ethernet frame specify?

A

defines the length of the Data field in the frame

34
Q

What is FCS in an Ethernet frame and what does it do?

A

Frame-check sequence and it provides a cyclic redundancy check (CRC) on all data in the frame

35
Q

What is some of the information that the ‘show version’ command provides?

A
Switch uptime
Model
IOS release
Reason for last reload
Interfaces and type
Memory installed
Base MAC address
36
Q

A VLAN is ?

A

a logical Local Area Network where devices could be anywhere on the network physically but, as far as they are concerned, they are all directly connected to the same switch

37
Q

If you want to connect to a switch over the network what do you have to do?

A

Add an IP address to a VLAN known as a management address

38
Q

What is the command to tell the switch where to send all IP traffic?

A

config t

ip default-gateway [gateway ip]

39
Q

What is the command to change the default name of the switch?

A

config t

hostname [some name]

40
Q

What are the commands to enable remote access to the switch?

A

config t

line vty 0 15

password [some password]

login

41
Q

What is the command to force only SSH connections to the switch?

A

config t

line vty 0 15

transport input ssh

42
Q

A LAN is essentially a ?

A

broadcast domain

43
Q

What are four advantages of VLANs?

A

faster network by containing broadcasts

saves resources on devices because they process less broadcasts

added security by keeping devices separate

flexibility in expanding devices across a geographical location of any size

44
Q

What is IEEE 802.1Q?

A

a vendor independent method to create interoperable VLANs also known as frame tagging.

45
Q

What is the limit to the number of VLANs that can be tagged using 802.1Q?

A

4096

46
Q

What is a port called that carries data from multiple VLANs?

A

a trunk

47
Q

What is a “native VLAN”?

A

A particular type of 802.1Q VLAN in which frames are not tagged.

48
Q

What are the two ways ports can be associated with VLANs?

A

statically

dynamically

49
Q

What is Cisco’s 802.1Q protocol called?

A

ISL

50
Q

Dynamic VLAN assignment allows devices to join a specific VLAN based on ?

A

the MAC address of the device

51
Q

Ports are assigned to ?

A

VLANs

52
Q

Devices are connected to ?

A

ports

53
Q

Switch ports or links can be of what type ?

A

Access

Trunk

Dynamic

54
Q

Access links typically connect the switch to ?

A

hosts

55
Q

VLAN trunks are used to carry data from ?

A

multiple VLANs

56
Q

What is the command to set a switch port to trunking?

A

switchport mode trunk

57
Q

What are the five possible modes a trunk link can be in?

A
On
Off
Auto
Desirable
No-negotiate
58
Q

Describe the On trunk mode

A

forces the port into permanent trunking mode. The port becomes a trunk, even if the connected device does not agree to convert the link into a trunk link.

59
Q

Describe the Off trunk mode

A

the link is not used as a trunk link, even if the connected device is set to “trunk.”

60
Q

Describe the Auto trunk mode

A

the port is willing to become a trunk link. If the other device is set to “on” or “desirable,” then the link becomes a trunk link. If both sides are left as “auto,” then the link will never become a trunk, as neither side will attempt to convert.

61
Q

Describe the Desirable trunk mode

A

the port actively tries to convert to a trunk link. If the other device is set to “on,” “auto,” or “desirable,” then the link will become a trunk link.

62
Q

Describe the No-negotiate trunk mode

A

prevents the port from negotiating a trunk connection. It will be forced into an access or trunk mode as per the configuration.

63
Q

What is the command to see which VLANs exist on a switch?

A

show vlan

64
Q

What is the command to label a VLAN?

A

vlan 5

name [some vlan name]

65
Q

What is the command to add port fa0/1 to VLAN 5?

A

interface fa0/1

switchport access vlan 5

66
Q

What is the command to verify which ports are trunking?

A

show interface trunk

67
Q

What is the command to change the native VLAN on trunking port?

A

switchport trunk native vlan [vlan#]

68
Q

What command deletes all VLAN info on a switch?

A

delete vlan.dat

69
Q

What is the first thing you should check if you cannot telnet to a switch?

A

whether telnet has been enabled using the ‘show run’ command and looking for ‘login’ or ‘login local’ and ‘password’ under the vty lines

70
Q

What is the first thing you should check if you cannot ping a switch?

A

That an IP address has been configured on the switch and that it has a default gateway

71
Q

What are signs of duplex mismatches?

A

input and CRC errors on the switch interface

72
Q

Switches contain a memory chip known as an _______, which builds a table listing which device is plugged into which port.

A

ASIC

73
Q

The _______ _______-_______-_______ command displays a list of which MAC addresses are connected to which ports.

A

show mac-address-table

74
Q

Which two commands add an IP address to the VLAN?

A

The interface vlan x command and the ip address x.x.x.x command.

75
Q

Which commands will enable Telnet and add a password to the switch Telnet lines?

A

Switch1( config)# line vty 0 15 Switch1( config-line)# password cisco Switch1( config-line)# login

76
Q

How do you permit only SSH traffic into your Telnet lines?

A

Use the Switch1( config-line)# transport input ssh command.

77
Q

What is the most likely cause of Telnet to another switch not working?

A

The authentication method is not defined on another switch.

78
Q

Switches remember all VLAN info, even when reloaded. True or False?

A

True

79
Q

A switch interface can be in which of three modes?

A

Trunk
Access
Dynamic

80
Q

How do you set a switch to be in a specific mode?

A

Apply the switchport mode command in Interface Configuration mode.

81
Q

Which commands will change the switch duplex mode and speed?

A

The duplex and speed commands.