01 - Network Models

Question 1

Protocols

Answer 1

sets of rules, regulations, standards, and procedures that enable hardware and software developers to make devices and applications that function properly at a particular layer

Question 2

OSI Seven Layers

Answer 2

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

Question 3

Layer 1

Answer 3

Physical Layer

- anything that moves data from one system to another (copper cabling, fiber optics, radio waves)

Question 4

NIC

Answer 4

Network Interface Card

- interface between PC and network

Question 5

MAC Address

Answer 5

• Media Access Control Address
• special firmware burned onto ROM chip
• 48-bit identifier
• no two NICs share the same MAC address
• first 6 digits - OUI - Organizationally Unique Identifier
• last 6 digits - Device ID

Question 6

View MAC address in Windows CLI

Answer 6

ipconfig /all

Question 7

View MAC address in Linux CLI

Answer 7

ip a

Question 8

View MAC address in Mac CLI

Answer 8

ifconfig

Question 9

Other names for MAC Address

Answer 9

• MAC-48

- EUI-48 (Extended Unique Indentifier)

Question 10

Frame

Answer 10

a container for a chunk of data moving across a network

Question 11

Unit of data at each layer is called?

Answer 11

PDU (Protocol Data Unit)

Question 12

PDU for Layer 2

Answer 12

Frame

Question 13

Different frame types

Answer 13

Different frame types are used on different networks, however, all NICs on the same network must use the same frame type

Question 14

Parts of a Frame

Answer 14

Header:

• Receiving MAC Address
• Sending MAC Address
• type field - indicates whats encapsulated in the frame

Payload:
- data

Trailer:
- FCS

Question 15

Frame Size

Answer 15

1500 bytes

Question 16

FCS

Answer 16

Frame Check Sequence

• 4 bytes long
• contains CRC
• tells recieving NIC if frame was received in good order

Question 17

Layer 2 Broadcast Address

Answer 17

FF-FF-FF-FF-FF-FF (6 sets)

Question 18

Unicast Address

Answer 18

Any frame addressed specifically to another device

Question 19

What is Layer 2

Answer 19

Data Link Layer

- any device that deals with MAC addresses

Question 20

Two jobs of a NIC

Answer 20

LLC

• Logical Link Control
• aspect of the NIC that talks to the OS via device drivers

Media Access Control
- creates and addresses Frames

Question 21

Physical vs Logical Addressing

Answer 21

Physical - MAC addresses

Logical - IP Addresses

Question 22

Network Protocol

Answer 22

uses logical addressing instead of physical addressing

Question 23

TCP/IP

Answer 23

Transmission Control Protocol / Internet Protocol

Question 24

What is Layer 3

Answer 24

Network Layer

- addresses packets to go from one network to another

Question 25

Layer 3 PDU

Answer 25

Packets

Question 26

How to routers route?

Answer 26

IP Addresses

Question 27

Chopping data up to send out on a network

Answer 27

Segmentation and Reassembly

Question 28

Transport Protocol data chunks

Answer 28

Segments (TCP/IP) - get sequence numbers

Datagrams (UDP) - no sequence

Question 29

What is Layer 4

Answer 29

Transport Layer

• segmentation/reassembly
• also requests packets that weren’t received in good order

Question 30

What is Layer 5

Answer 30

Session Layer

• initiates, accepts, opens and closes sessions
• connects applications to applications

Question 31

View sessions windows CLI

Answer 31

netstat -a

Question 32

What is Layer 6?

Answer 32

Presentation Layer

- translates data from lower layers into a format usable by the application layer, and vice versa

Question 33

What is Layer 7?

Answer 33

Application Layer

• code built into all OSs that enable network aware applications
• done through APIs (Application Programming Interfaces)