OSI Flashcards

1
Q

What is layer 7 of the OSI model?

A

application

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2
Q

What layer number is the Application layer of the OSI model?

A

7

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3
Q

What is layer 6 of the OSI model?

A

presentation

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4
Q

What layer number is the Presentation layer of the OSI model?

A

6

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5
Q

At which OSI layer is encryption / decryption?

A

6 or presentation

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6
Q

At which OSI layer is data compression?

A

6 or presentation

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7
Q

What is layer 5 of the OSI model?

A

session

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8
Q

What layer number is the Session layer of the OSI model?

A

5

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9
Q

What is layer 4 of the OSI model?

A

transport

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10
Q

What layer number is the Transport layer of the OSI model?

A

4

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11
Q

What does MTU stand for?

A

maximum transmission unit

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12
Q

What is the typical value for MTU (in bytes)?

A

1500

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13
Q

At which OSI layer are software ports?

A

4|transport

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14
Q

What does TCP stand for?

A

transmission control protocol

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15
Q

Which protocol provides for guaranteed delivery of information?

A

tcp

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16
Q

At which OSI layer is TCP?

A

4|transport

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17
Q

Which protocol provides for fast (but not guaranteed) delivery of information?

A

udp

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18
Q

What does UDP stand for?

A

user datagram protocol

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19
Q

At which OSI layer is UDP?

A

4|transport

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20
Q

At which OSI layer do we find segments?

A

4|transport

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21
Q

What is the Protocol Data Unit at OSI layer 4?

A

segment

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22
Q

What is layer 3 of the OSI model?

A

network

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23
Q

What layer number is the Network layer of the OSI model?

A

3

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24
Q

At which OSI layer is the Internet?

A

3 or network

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25
Q

At which OSI layer are Wide Area Networks?

A

3 or network

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26
Q

What does WAN stand for?

A

Wide Area Network

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27
Q

At which OSI layer is IP Addressing?

A

3 or network

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28
Q

What does IP stand for?

A

internet protocol

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29
Q

At which OSI layer is Logical Addressing?

A

3 or network

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30
Q

At which OSI layer does a router operate?

A

3 or network

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31
Q

At which OSI layer does a gateway operate?

A

3 or network

32
Q

At which OSI layer is Network Address Translation?

A

3 or network

33
Q

At which OSI layer is Port Address Translation?

A

3 or network

34
Q

At which OSI layer do we find packets?

A

3 or network

35
Q

What is the Protocol Data Unit at OSI layer 3?

A

packet

36
Q

What is layer 2 of the OSI model?

A

datalink

37
Q

What layer number is the Data Link layer of the OSI model?

A

2

38
Q

What does MAC stand for?

A

media access control

39
Q

How does a typical laptop computer discover its own MAC address?

A

It already knows it. It is burned in on the network card.

40
Q

What does NIC stand for?

A

network interface controller

41
Q

At which OSI layer is the Local Area Network?

A

2 or datalink

42
Q

At which OSI layer is MAC Addressing?

A

2 or datalink

43
Q

At which OSI layer is Physical Addressing?

A

2 or datalink

44
Q

At which OSI layer is Ethernet?

A

2 or datalink

45
Q

At which OSI layer does a switch operate?

A

2 or datalink

46
Q

At which OSI layer does a bridge operate?

A

2 or datalink

47
Q

What is a multi-port bridge called?

A

switch

48
Q

What is a two-port switch called?

A

bridge

49
Q

At which OSI layer do we find frames?

A

2 or datalink

50
Q

What is the Protocol Data Unit at OSI layer 2?

A

frame

51
Q

What is layer 1 of the OSI model?

A

physical

52
Q

What layer number is the Physical layer of the OSI model?

A

1

53
Q

At which OSI layer is wireless signal?

A

1 or physical

54
Q

At which OSI layer is coaxial cable?

A

1 or physical

55
Q

At which OSI layer is cat5 cable?

A

1 or physical

56
Q

At which OSI layer is fiber-optic cable?

A

1 or physical

57
Q

What is a multi-port repeater called?

A

hub

58
Q

What is a two-port hub called?

A

repeater

59
Q

At which OSI layer does a hub operate?

A

1 or physical

60
Q

At which OSI layer does a signal repeater operate?

A

1 or physical

61
Q

At which OSI layer do we find bits?

A

1 or physical

62
Q

What is the Protocol Data Unit at OSI layer 1?

A

bits

63
Q

What is a hop?

A

A hop is the moving of a packet from one LAN to another.

64
Q

What does TTL stand for?

A

time to live

65
Q

What is the purpose of TTL?

A

It reduces the risk of network loops.

66
Q

What does having a routable address mean?

A

Packets can be sent to you across the Internet just using your own IP address.

67
Q

List the five non-routable IP address blocks

A

10.0.0.0/8, 127.0.0.0/8, 169.254.0.0/16, 172.16.0.0/12, 192.168.0.0/16

68
Q

What does NAT stand for?

A

network address translation

69
Q

What does PAT stand for?

A

port address translation

70
Q

Explain Man In The Middle?

A

Man in the middle is (a) hacking technique. (b) Two computers believe they are talking to each other. Instead they are talking through (by way of) a third computer.

71
Q

In NAT, how does the router remember the original sender?

A

The router keeps a table that matches outside port numbers with inside IP address and port number pairs.

72
Q

What is garbage collection?

A

Reclaiming resources that are no longer in use.

73
Q

How long do NAT address pool entries last?

A

Address pool entries often expire (a) after ten minutes, or (b) when the table is full the most stale entry expires.

74
Q

What is a keep-alive?

A

A keep-alive is a message that is sent between two computers just to keep the connection from timing out and being dropped.

75
Q

What does DMZ stand for?

A

demilitarized zone