OSI Layers

Question 1

OSI layer 1

Answer 1

Physical

Transmits binary over physical media between devices

Question 2

OSI layer 2

Answer 2

Data link

Creates and address frames for host to host delivery on LANd and between WANs

Question 3

OSI layer 3

Answer 3

Network

Creates and addresses packets for delivery between devices

Question 4

OSI layer 4

Answer 4

Transport

Defines data segments and numbers them at the source, transfers the data, and reassembles the data at the destination.

Question 5

OSI layer 5

Answer 5

Session

Manages sessions between users and synchronizes web sessions, video, etc.

Question 6

OSI layer 6

Answer 6

Presentation

Provides data format info to the application

I.e. whether it is a jpg or encrypted etc.

Question 7

OSI layer 7

Answer 7

Application

Performs services for applications used by the user

Question 8

Acronym for remembering the OSI layers

Answer 8

All people seem to need data processing

Question 9

What layer uses frames?

Answer 9

Layer 2 data link

Question 10

What layer uses packets?

Answer 10

Layer 3 network

Question 11

TCP/IP layer 1

Answer 11

Network access(OSI 1&2)

Question 12

TCP/IP layer 2

Answer 12

Internet (OSI 3)

Question 13

TCP/IP layer 3

Answer 13

Transport (OSI 4)

Question 14

TCP/IP layer 4

Answer 14

Application (OSI 5-7)

Question 15

What is used to identify an application at the transport layer?

Answer 15

Port #

Question 16

2 transport layer protocols

Answer 16

TCP-uses segments, connection oriented

UDP-best effort, uses data grams

Question 17

Well known ports

Answer 17

Reserved for services and applications

0-1023

Question 18

Registered ports

Answer 18

Assigned to user processes or applications

1024-49151

Question 19

Dynamic or private ports

Answer 19

Assigned dynamically to client applications when initiating a connection

49152-65535

Question 20

FTP

Answer 20

TCP

Port 20/21

Question 21

Telnet

Answer 21

TCP

Port 23

Question 22

Smtp

Answer 22

Smtp

TCP

Port 25

Question 23

TFTP

Answer 23

Trivial file transfer protocol

UDP

Port 69

Question 24

HTTP

Answer 24

Hypertext transfer protocol

TCP

Port 80

Question 25

POP3

Answer 25

Post office protocol TCP Port 110

Question 26

IMAP

Answer 26

Internet message access protocol Port 143 Port 993 w/ssl TCP

Question 27

HTTPS

Answer 27

Secure http | Port 443

Question 28

Causes of physical layer problems

Answer 28

``` Power related Hardware faults Cabling faults Attenuation Noise Interface config errors Exceeding design limits CPU overload ```

Question 29

Symptoms of data link problems

Answer 29

No functionality of network layer or above Poor performance Excessive broadcasts Console messages

Question 30

Causes of data link problems

Answer 30

Encapsulation errors Address mapping errors Framing errors Stp failures or loops

Question 31

TCP/IP application layer protocols

Answer 31

DNS, telnet, SMTP, POP3, IMAP, DHCP, HTTP, FTP, SNMP

Question 32

TCP/IP transport protocols

Answer 32

TCP/IDP

Question 33

TCP/IP Internet layer protocols

Answer 33

IP, ARP, ICMP

Question 34

TCP/IP network access layer protocols

Answer 34

Ethernet, frame relay

Question 35

Application layer PDU

Answer 35

Data

Question 36

Transport layer PDU

Answer 36

Segment

Question 37

Internetwork layer PDU

Answer 37

Packet

Question 38

Network access layer PDU

Answer 38

Frame

Question 39

What layer do client/server processes reside in?

Answer 39

Application

Question 40

Primary responsibilities of transport layer

Answer 40

Tracking individual communications between applications on the source and destination hosts Segmenting data and managing each piece Reassembling the segments into streams of application data Identifying different applications Flow control between end users Enabling error recovery Initiating a session

Question 41

3 key functions of physical layer

Answer 41

Physical components Encoding Signaling

Question 42

Code group

Answer 42

A symbol that is a predefined small group of bits that represent a larger group of data bits at the physical layer

Question 43

2 Ethernet data link sub layers

Answer 43

LLC logical link control MAC media access control

Question 44

LLC

Answer 44

Implemented on software Adds control information to network layer packet

Question 45

MAC

Answer 45

Implemented in hardware, typically the NIC Data encapsulation Placement of frames on media

Question 46

MAC address

Answer 46

48 bit binary # expressed in hex 1st 3 bytes are vendor code Last 3 bytes are unique #

Question 47

Broadcast MAC address

Answer 47

FF-FF-FF-FF-FF-FF 48 1s in binary

Question 48

ARP

Answer 48

Address resolution protocol Uses a broadcast at layer 2 to discover the MAC address of the host when a layer 3 address is known Maintains a cache of mapping

Question 49

Multicast MAC address

Answer 49

Always beginning with 01-00-SE