Ccna - (3) - Osi Model & Tcp/ip Model

Front 1

What is OSI Model short for?

Back 1

Open Systems Interconnect Model

Front 2

What are the 7 OSI model layers?

Back 2

Application
Presentation
Session
Transport
Network
Data Link
Physical

Front 3

What are the upper layers?

Back 3

Application
Presentation
Session

Front 4

What are the lower layers?

Back 4

Transport
Network
Data Link
Physical

Front 5

What does the OSI Application layer do?

Back 5

Provides network services to the end host's applications

eg - Email, FTP, Telnet

Front 6

What does the OSI Presentation layer do?

Back 6

Ensures that data can be understood between two end hosts

eg - ASCII character encoding

Front 7

What does the OSI Session layer do?

Back 7

Manages sessions between end hosts

eg - Web server tracking its open connects to web browser clients

Front 8

What does the OSI Transport layer do?

Back 8

1) Breaks up data between sender and receiver into smaller parts
2) Establishes end to end connectivity
3) Can ensure reliable delivery (ie - error detection and retransmission)

Front 9

What is segmentation?

Back 9

The process used by Layer 4 (Transport layer) to break data between sender and receiver into smaller parts

Front 10

Name two layer 4 protocols

Back 10

TCP (Transmission Control Protocol)
UDP (User Datagram Protocol)

Front 11

What OSI layer do TCP and UDP work at?

Back 11

Layer 4 (Transport)

Front 12

What does the OSI Network layer do?

Back 12

- Provides connectivity and path selection (eg - routing)
- Defines logical addressing (eg - IPv4 and IPv6 addresses)

Front 13

What layer do IPv4 and IPv6 work at?

Back 13

Layer 3 - Network layer

Front 14

What does the OSI Data Link layer do

Back 14

- Defines data format for transmission (eg - Ethernet, Frame Relay, PPP)
- Controls access to physical media (eg - Ethernet CSMA/CD)
- Defines physical addressing (eg - ethernet MAC address)
- Typically has error detection (eg - Cyclical Redundancy Check (CRC))

Front 15

What are Data Link layer protocols

Back 15

Ethernet
PPP

Front 16

What does the OSI Physical layer do?

Back 16

- Defines physical media properties
* Electrical Functions
* Physical data rates
* Physical connectors
* Cable distances
* Optical wavelengths
* Wireless frequencies

Front 17

What layer do Repeaters and Hubs work at?

Back 17

Layer 1 - Physical

Front 18

Why use layers?

Back 18

- Devices need to be aware only of their own layer
- Allows interoperability between devices and vendors

Front 19

What is encapsulation

Back 19

This is where data is added when adjacent layers talk. Happens during sending data

Front 20

Name the process where data is removed when adjacent layers talk

Back 20

Decapsulation

Front 21

What is a PDU?

Back 21

A Protocol Data Unit - it is the resulting data that a layer creates

Front 22

What happens during decapsulation?

Back 22

The process removes data formatting on the receiving host to expose a PDU

Front 23

What is a PDU at the Transport layer called?

Back 23

A Segment

Front 24

What is a packet?

Back 24

A PDU at layer 3 (Network layer)

Front 25

What is a frame?

Back 25

A PDU at layer 2 (Data Link layer)

Front 26

What is a PDU at layer 1 called?

Back 26

A Bit

Front 27

What direction does encapsulation occur?

Back 27

From layer 7 to layer 1

Front 28

What is an encapsulation header?

Back 28

New data added to the front by a layer during encapsulation

Front 29

What is an encapsulation trailer?

Back 29

New data added to the end by a layer during encapsulation

Front 30

Describe the decapsulation process

Back 30

- Data moves up the stack (layer 1 -> 7)
- Each layer removes its own header/trailer
- Data is passed to the layer above
- Process repeats until data reaches the application layer

Front 31

What is the TCP/IP Model?

Back 31

- Similar to OSI model but just 4 layers. 4 layers known as the TCP/IP stack or just IP stack

Front 32

What are the 4 TCP/IP model layers?

Back 32

* Application
* Transport
* Internet
* Network Access

Front 33

Which TCP/IP model layer is equivalent to OSI layers 5 - 7?

Back 33

Application

Front 34

What does the TCP/IP Application layer do?

Back 34

Provides network Application Programming Interface (API)

Front 35

What does the TCP/IP Transport layer do?

Back 35

Provides communication to the application.

- Equivalent of OSI layer 4

Front 36

What is TCP?

Back 36

Transmission Contol Protocol

- Used for connection-oriented reliable communication (eg - Database replication)

Front 37

What is UDP?

Back 37

User Datagram Protocol

- Used for connectionless unreliable communication (eg - VOIP)

Front 38

What does the TCP/IP Internet layer do?

Back 38

Provides packet addressing, routing, fragmentation and reassembly

- Equivalent of OSI layer 3

Front 39

What does the TCP/IP Network Access layer do

Back 39

Equivalent of OSI layers 1 & 2