The OSI seven-layer model

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Quick Questions

Shade in the A or B circle for each question.

1. Which list shows the OSI layers in order from layer 1 up to layer 7?

A Physical, network, data link, transport, presentation, session, application

B Physical, data link, network, transport, session, presentation, application

2. How many layers does the OSI model have?

A Four

B Seven

3. Which layer is layer 1 (the bottom layer) of the OSI model?

A Physical

B Application

4. Which OSI layer is responsible for IP addressing and choosing a route for packets between networks?

A Network layer (layer 3)

B Data link layer (layer 2)

5. Which OSI layer uses MAC addresses to deliver frames between devices on the same local network?

A Data link layer

B Transport layer

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Layer 1: Physical		APhysical, Data Link, Network, Transport, Session, Presentation, Application
2Layer 4: Transport		BThe bottom OSI layer, which sends raw bits as electrical, light or radio signals over the medium.
3The seven OSI layers listed from the bottom (layer 1) up to the top (layer 7)		CLayer 7 is the Application layer at the top. The Physical layer is layer 1 at the bottom.
4The seven OSI layers listed top-down, in the order data moves when it is sent from an application		DThe OSI layer that splits data into segments and manages delivery between devices using ports (TCP or UDP).
5Layer 7 is the Physical layer, at the bottom of the OSI model		ENetwork and Data Link are in the wrong order. Layer 2 is Data Link and layer 3 is Network.
6OSI order from layer 1: Physical, Network, Data Link, Transport		F7 Application, 6 Presentation, 5 Session, 4 Transport, 3 Network, 2 Data Link, 1 Physical

Definitions

OSI model

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Layer 1: ________ (cables and signals)

Layer 2: _________ (MAC addresses, frames)

Layer _: Network (IP addresses, routing)

Layer 4: _________ (TCP and UDP)

Layer 5: Session Layer 6: ____________ Layer 7: Application

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A print("OSI layers, bottom up")

B print("1 physical")

C print("2 network")

D print("3 network")

Question 2

A layer = 1

B name = "application"

C print(layer, name)

Question 3

A layer = 3

B name = "network"

C print(layer, name)

D job = "bit signals on cable"

Question 4

A order = "top-down"

B first = "application"

C second = "presentation"

D third = "transport"

E last = "physical"

Question 5

A order = "bottom-up"

B first = "physical"

C second = "network"

D third = "network"

Answer Key

The OSI seven-layer model

Section A: Quick Questions

B — Physical, data link, network, transport, session, presentation, application

B — Seven

A — Physical

A — Network layer (layer 3)

A — Data link layer

Section B: Match the Pairs

Layer 1: Physical → The bottom OSI layer, which sends raw bits as electrical, light or radio signals over the medium.

Layer 4: Transport → The OSI layer that splits data into segments and manages delivery between devices using ports (TCP or UDP).

The seven OSI layers listed from the bottom (layer 1) up to the top (layer 7) → Physical, Data Link, Network, Transport, Session, Presentation, Application

The seven OSI layers listed top-down, in the order data moves when it is sent from an application → 7 Application, 6 Presentation, 5 Session, 4 Transport, 3 Network, 2 Data Link, 1 Physical

Layer 7 is the Physical layer, at the bottom of the OSI model → Layer 7 is the Application layer at the top. The Physical layer is layer 1 at the bottom.

OSI order from layer 1: Physical, Network, Data Link, Transport → Network and Data Link are in the wrong order. Layer 2 is Data Link and layer 3 is Network.

Section C: Definitions

OSI model — A seven-layer network model: physical, data link, network, transport, session, presentation, application. Layer 1 is physical (bottom) and layer 7 is application (top).

Section D: Fill in the Blanks

Layer 1: Physical (cables and signals)

Layer 2: Data Link (MAC addresses, frames)

Layer 3: Network (IP addresses, routing)

Layer 4: Transport (TCP and UDP)

Layer 5: Session
Layer 6: Presentation
Layer 7: Application

Section E: Spot the Error

C — Layer 2 is the data link layer. The network layer is layer 3, so line 3 should be print("2 data link").

B — Layer 1 is the physical layer at the bottom of the OSI model. The application layer is layer 7 at the top. The line should be name = "physical".

D — The network layer handles IP addressing and routing. Sending bit signals over a cable is the job of the physical layer.

D — Going top-down the order is application (7), presentation (6), session (5). Transport is layer 4, so it comes after session. The line should be third = "session".

C — Going bottom-up, layer 2 is data link, directly above physical. The network layer is third. The line should be second = "data link".