Chapter 2 - Network Models

Question 1

What is the OSI Model

Answer 1

Open Systems Interconnection enables us to follow a model to explain almost any type of network including long obscure old ones.

Question 2

Define Protocol

Answer 2

A set of rules, regulations, and standards that enable hardware and software developers to make devices and applications that will function at a particular level

Question 3

What are the Seven layers of the OSI Model

Answer 3

7 = Application
6 = Presentation
5 = Session
4 = Transport
3 = Network
2 = Data Link
1 = Physical

Question 4

What is a way to remember the seven layers (mneomonics)

Answer 4

All People Seem To Need Data Processing

Question 5

What is part of layer one

Answer 5

Cabling, radio waves, central boxes (hubs, switches, etc.). Doesn’t care what the data is, only moves it from place to place

Question 6

What makes a NIC unique

Answer 6

48 bit Media Access Control number made up of hexdecimal digits

Question 7

What are the two parts to a MAC address

Answer 7

First 6 digits identify the manufacturer, Organizationally Unique Identifier
Last 6 digits identify the unique serial number

Question 8

Who gives out MAC addresses

Answer 8

IEEE, Institute of Electronic and Electrical Engineers

Question 9

How does Hexadecimal work with binary

Answer 9

Four bits = 1  character
0000 = 0
0001 = 1
1000 = 8
1111 = 15

Question 10

What is the Organizationally Unique Identifier (OUI)

Answer 10

Used in the first 6 digits of a MAC address to identify the manufacturer

Question 11

What is another name for MAC-48

Answer 11

EUI - 48 , Extended Unique Identifier

Question 12

What is a frame

Answer 12

A container for a chunk of data moving across the network

Question 13

Where is a frame created

Answer 13

The NIC

Question 14

What does a frame look like

Answer 14

Recipient MAC | Sender MAC | Type | Data | FCS

Question 15

What is FCS

Answer 15

Frame Checking Sequence, uses binary math (cyclic redundancy check) when recieving to verify that data is all intact

Question 16

How much data can a frame contain?

Answer 16

1500 bytes (average)

Question 17

How does a Hub operate

Answer 17

A hub makes an exact copy of the frame and broadcasts it to all system connected. The receiving system is the only one that will process the data.

Question 18

How does a switch operate

Answer 18

Sends the frame to the proper destination only.

Question 19

What is a way to think of Cyclic Redundancy Checks

Answer 19

It is similar to the remainder of a division problem

Question 20

What is a broadcast address

Answer 20

FF-FF-FF-FF-FF-FF, every NIC will process this.

Question 21

What is considered to be part of layer 2

Answer 21

Any device that deals with a MAC is part of layer 2

Question 22

What does the Data link layer provide as a service

Answer 22

Data Link Control

Question 23

What are the two jobs of the NIC

Answer 23

Logical Link Control, and Media Access Control

Question 24

What is Logical Link control (LLC)

Answer 24

Talks with the system OS (usually drivers), handles network protocols and provides flow control

Question 25

TCP/IP is considered a network protocol, but is actually...

Answer 25

a protocol suite, can be used to explain many protocols

Question 26

What happens at layer 3

Answer 26

Containers called packets are created and addressed enabling them to go from one network to the other. This is the last layer that deals with hardware

Question 27

What happens with an IP packet

Answer 27

Packet handed to NIC and enclosed within a frame.

Question 28

What does a packet look like in contrast to a frame

Answer 28

IP Header | TCP Header | Segment OR IP Header | UPD Header | Message

Question 29

Why would a packet be stripped away from the frame and put into a new frame

Answer 29

This is so it will be the appropriate technology for its next destination but the IP packet will never change

Question 30

What connects the NIC to the System

Answer 30

Driver software

Question 31

What happens in layer 4

Answer 31

Data is broken in to chunks called segments or datagrams depending on the protocol. Each chunk is given a sequence number. Think of it as the assembler disassembler software.

Question 32

What happens in layer 5

Answer 32

Handles all the sessions incoming/outgoing in a system. Sessions are opened and closed here.

Question 33

What happens in layer 6

Answer 33

Incoming data is translated to be used by software and applications, vice versa for outgoing

Question 34

What happens in layer 7

Answer 34

This is the programming that enables application to be network aware.

Question 35

What is encapsualtion

Answer 35

The process of preparing data to go onto the network

Question 36

What is de-encapsulation

Answer 36

preparing data too be used by the system

Question 37

What are the four layers of the TCP/IP Model

Answer 37

Application Transport Internet Link/Network interface

Question 38

What is a difference between OSI model and the TCP/IP Model

Answer 38

OSI is prescriptive, TCP/IP is descriptive

Question 39

Explain the Link/Network interface layer (TCP/IP)

Answer 39

Similar to Layer 1 & 2 of the OSI model Handles all the physical connections Cabling, hubs, switches, etc.

Question 40

Explain the internet layer (TCP/IP)

Answer 40

Any device or protocol that deals with pure IP packets. Any device or protocol that deals with getting the IP packets to its destination. Similar to the Network layer of the OSI model

Question 41

Expalin the Transport layer (TCP/IP)

Answer 41

Combines Session and Transport (hint of application) from the OSI model Involved in the assembly and disassembly of data

Question 42

What is a connectionless protocol

Answer 42

TCP, Transmission Control Protocol

Question 43

What is a connection oriented protocol

Answer 43

UDP, User datagram protocol

Question 44

What si a TCP segment

Answer 44

What is left after a the IP is stripped from an IP packet. Make sure data gets to the destination in the right order using a checksum, flags, and acknowledgment.

Question 45

What does a TCP segment look like

Answer 45

Destination Port | Source Port | Sequence Number | Checksum | Flag | Acknowledgement | Data

Question 46

Where does TCP get is data from

Answer 46

The transport layer (OSI) or internet layer (TCP)

Question 47

What does UDP get its data from

Answer 47

Applcation layer

Question 48

What does a UDP datagram look like

Answer 48

Destination port | Source Port | Length | Checksum | data

Question 49

What is the range of prots TCP/IP uses

Answer 49

1 - 65535

Question 50

Link layer matches with which data structure

Answer 50

Frame

Question 51

Internet layer matches with which data structure

Answer 51

IP packet

Question 52

Transport layer matches with which data structure

Answer 52

TCP/IP segment or UDP datagram

Question 53

Application layer matches with which data structure

Answer 53

Data starts and ends here

Question 54

What does an IP Header contain

Answer 54

Source IP Address & Destination IP Address

Question 55

What does a TCP/UDP Header contain

Answer 55

Source Port & Destination Port