LAN Switching Fundamentals Flashcards

1
Q

What is a Broadcast Domain?

A

A broadcast domain contains all devices that can reach each other at the data link layer (OSI layer 2) by using broadcast.

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2
Q

What is a Collision Domain?

A

Collection of devices that all share the same medium ie switch or hub.

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3
Q

What are the two major ways that traffic is able to be sent over the same wire with multiple host?

A

Time Division Multiplexing (Alternates signals from host so each signal has a certain amount of time before the next signal is put on the wire) and Frequency Division Multiplexing (IE Radios)

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4
Q

What is CSMA/CA?

A

Carrier Sense Multiple Access with Collision Detection

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5
Q

What is it called when on a communication link only one person can talk and then goes quiet while someone else talks and then talks again when it’s their turn?

A

Half Duplex

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6
Q

What is called when both sides of a communication link are able to talk at the same time?

A

Full Duplex

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7
Q

What is Carrier Sense?

A

When a host is listening to a wire to see if it detects 1’ and 0’s on it and if so it must be quiet

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8
Q

If Carrier Sense detects no 0’s or 1’s it must do what before putting 0’s and 1’s on the wire?

A

Wait a specific amount of time to make sure no one else starts talking first.

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9
Q

What is a MTU?

A

Maximum Transmission Unit, the maximum size of any data unit.

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10
Q

What is it when all devices have access to a wire and anyone can talk?

A

Multiple Access

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11
Q

What happens if collision is detected on a wire?

A

The transmission is stopped wherever it is and then the time to wait before putting a signal on the wire is widen a bit before trying again and will repeat this process 16 times before dropping the signal all together.

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12
Q

What is the structure of a DIX Ethernet Frame?

Bonus how many bytes for each field?

A

Preamble(8) | Destination Address(6) | Source Address(6) | Type(2) | Data (or Padding)(46 - 1500) | FCS(4)

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13
Q

What is the Preamble?

A

A constant pattern at the beginning of an ethernet frame that acts as a wake up call saying “Hey here come an ethernet packet”

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14
Q

What is the structure of a IEEE 802.3 Ethernet Frame?

Bonus how many bytes for each field?

A

Preamble(7) | Start of Frame Delimiter (1) | Destination Address (6) | Source Address (6) | Length(2) | 802.2 Header + Data (46-1500) | FCS (4)

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15
Q

How many bits are in a MAC Address?

A

48 bits

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16
Q

What are the first 24 bits called?

A

The Organizationally Unique Identifier

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17
Q

The last 24 bits of a MAC Address on a NIC Card are?

A

Unique within the organization.

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18
Q

In the first byte (1E Below) of a MAC Address the first two bits are very important, what does each bit represent?

1E:4B:2A:3A:BB:CA

A

Bit 1: Individual or Group bit.
If set to a 0 it’s an individual MAC Address. If it’s set to 1 it’s a group MAC Address , ie MAC broadcast FF:FF:FF:FF:FF:FF

Bit 2: The Global or Local bit
If set to 0 it’s a global address and if it’s set to 1 it’s a local address. The bit that is flipped during EUI-64

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19
Q

What is a Straight-Through Cable and when is it used?

A

Where pin 1 on one side goes to pin 1 on the other side and the same goes for all 8 pins.

Used when connecting devices that are at different OSI Model Layers

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20
Q

What is a Cross-Over Cable and when is it used?

A

Pin 1 goes to Pin 3
Pin 2 goes to Pin 6
Rest of the pins match up

Used when connecting devices at similar OSI Model Layers

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21
Q

What is a Rolled Cabled and when is it used?

A

The pins are reversed, pin 1 on one side goes to pin 8 on the other and you do that all the way down.

Used when connecting devices to console ports, not meant for ethernet frames.

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22
Q

What is a switch?

A

Networking device that connects devices together on a computer network by using packet switching to receive, process, and forward data to the destination device. Allows for different speeds on different ports.

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23
Q

How does a switch handle collision?

A

Separates the collision domains. Each port has memory for a receive and transport buffer so that if frames come in at the same time the port waits until it’s turn and then either sends or receives that frames.

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24
Q

What layer does a switch operate at?

A

The data link layer (2)

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25
Q

What is a MAC Address Table and how is it used?

A

Stored addresses within a switch that are learned from plugging the device into it for the first time. It uses this to know where to forward traffic to.

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26
Q

What is the amount of time a Cisco switch will wait before forgetting a MAC Address after not seeing it?

A

5 minutes.

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27
Q

The forwarding of frames is based off of the what?

A

The Destination MAC Address

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28
Q

What is the start up process switches and routers generally go through?

A
  1. Discover device hardware
  2. Find and load IOS Image
  3. Find and load config file
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29
Q

By default where is the IOS stored?

A

In flash memory.

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30
Q

By defualt where is the Start-up Config File stored?

A

In NVRAM memory

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31
Q

Which two memory typed retain their information even if the system is powered off?

A

Flash and NVRAM (Non-Volatile Random Access Memory)

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32
Q

Where is the IOS and Start-up config copied to when the device is running?

A

To the DRAM

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33
Q

What are the speeds and sizes of Flash, NVRAM, and DRAM?

A

Flash: Moderate Size, slow speed
NVRAM: Small Size, slow speed
DRAM: Large size, fast speed

34
Q

What do you have to do with the running config after making changes to it?

A

Save it to the start-up config

Command:

switch# write memory

35
Q

Where are the tables for the device (ie routing tables, MAC Address Tables, ARP Tables) stored?

A

DRAM

36
Q

What mode is this?

Switch>

A

User or Exec Mode

37
Q

What mode is this?

Switch#

A

Privileged Exec Mode or Enable Mode

38
Q

What configuration mode is this?

Switch(config)#

A

Global Configuration Mode

39
Q

What configuration mode is this?

Switch(config-if)#

A

Interface Configuration Mode

40
Q

What is the command to determine the amount of line that show on a show command?

A

Switch#terminal length (0-512)

41
Q

What is the command to take you all the way back to Privileged Exec Mode?

A

Switch(config-if)# end

42
Q

What is the command to take you back one level in the CLI?

A

Switch(config-if)#exit

Switch(config)#

43
Q

What is the command to prevent syslog and event messages?

A

Switch(config-line)# logging synchronous

44
Q

What is the command to prevent DNS resolution for mistyped commands?

A

Switch(config)# no ip domain-lookup

45
Q

What is the command to set the hostname?

A

Switch(config)# hostname

46
Q

What is the command to set a banner?

A

Switch(config)# banner motd

47
Q

What is the command to add an IPv4 Address to an interface?

A

Switch(config-if)#ip address <address></address>

48
Q

What’s the command to bring an interface up and down?

A

(To shut it down)

Switch(config-if)#shutdown

and to bring it up

Switch(config-if)#no shutdown

49
Q

What is the very first thing that is checked when a device starts up to learn where to find it’s config files and everything?

A

Configuration Register

50
Q

What is the command to show the IOS version that is running?

A

Switch# show version

51
Q

What is the command to display all memory locations and file names?

A

Switch# directory all

52
Q

What is the command to show the saved and current running configs?

A

Switch# show startup-config

and

Switch# show running-config

53
Q

How do you save your running config to the startup config?

A

Switch# copy running-config startup-config

copy

or

Switch# write memory

54
Q

How do you set a device back to factory default?

A

Step 1. Delete Startup Config:
Switch#erase startup-config
or
Switch# write erase

Step 1a. (Switch only):
Switch# delete flash:vlan.dat

Step 2. Reload the device:
Switch# Reload

55
Q

What are the two password commands and their differences?

A

Switch(config)# enable password
This stores password in plain text

Switch(config)# enable secret
Encrypts the password you entered

56
Q

How do you configure a console password?

A

Switch(config)# line console 0

Switch(config-line)# password

57
Q

What port does TCP port does telnet come in on?

A

Port 23

58
Q

What are the commands to set 1 password on your VTY lines?

A

Switch(config)# line vty 0 4
Switch(config-line)#password
Switch(config-line)#login

59
Q

What are the commands to set up usernames and password for your VTY lines?

A

Switch(config)#username privilege 15 password

Switch(config)#login local

60
Q

What is CDP?

A

Cisco Discovery Protocol. Layer 2 protocol for neighbor discovery that provides information such as OS Version, interface, and IP Address.

61
Q

What is the default timer for CDP?

A

60 seconds

62
Q

What is LLDP?

A

Link Layer Discovery Protocol, opened standard version of CDP.

63
Q

What is a VLAN?

A

Logical group of workstations, servers and network devices that appear to be on the same LAN despite their geographical distribution

64
Q

What does a VLAN provide?

A

Separates broadcast domains, provides better security, and provides hierarchical subnet usage.

65
Q

What is the VLAN range?

A

1-4094

66
Q

What is the normal usable VLAN range?

A

1-1001

67
Q

What VLANs are reserved for token ring?

A

1002-1005

68
Q

What is the range of the extended range VLANS?

A

1006-4094

69
Q

What is the command to configure a VLAN?

A

Switch(config)#vlan

Switch(config-vlan)#name

70
Q

What is an access port?

A

A switchport that is configured only for a single broadcast domain.

71
Q

What is a Trunk Port?

A

A switchport that can have two or more vlans configured on it that can allow multiple VLAN information to pass through it.

72
Q

What is 802.1Q Encapsulation?

A

All traffic except for the native VLAN is inserted with a 802.1Q Tag (in the type field) to let the switch know which VLAN the packet is coming from .

73
Q

By default what is the native VLAN?

A

Vlan 1

74
Q

What command changes the native VLAN?

A

Switch(config-if)#switchport truck native vlan

75
Q

What is the Auto mode of trunking?

A

If the other end asks me to be a trunk with DTP, then become a trunk, but I wont initiate any negotitation from this end. If no one asks me to become a trunk then I will become an access port

76
Q

What is the desirable mode?

A

Ask the other end to trunk using DTP and trunk if the negotiation succeeds. If DTP negotiation fails then become an access port

77
Q

What is the On mode of trunk?

A

Always trunk on this end, and I will send DTP to attempt to negotiate a trunk on the other end

78
Q

Port security is not available on what type of ports?

A

Dynamic Ports

79
Q

What does port security offer?

A

Limited access to switch ports by limiting which MAC addresses can access a port or the number of MAC addresses

80
Q

What are the 3 outcomes if a security violation occurs?

A
  1. Shutdown (defualt)
  2. Protect (if a frame comes in that is a violation it will just drop the frame.)
  3. Restrict (Creates a log of the violations as they happen and acts as Protect mode as well.)
81
Q

What is a ports default behavior for port security?

A

Ports do not perform security checks and just pass all traffic.