Tracing data across a network

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Which is the correct order for a message going from your device to a website?

A Device, router, ISP, server

B Device, server, router, ISP

2. What does the router do at the start of the data path?

A It passes data from your device on to the ISP

B It stores the website for your device

3. When a server answers your request, where does the reply go?

A It stays on the server until you ask again

B It travels back along the route to your device

4. True or false: Data jumps straight from your device to a server without passing through other devices.

A True

B False

5. In a diagram of the data path, what do the arrows show?

A The direction the data travels

B How fast each device is

Match the Pairs

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

Left column		Right column
1device -> router -> ISP -> server		AThe reply travelling back along the route to the device that sent the request
2server -> ISP -> router -> device		BThe path only shows the data going one way. The server sends a reply that travels back along the route (server -> ISP -> router -> device), so the diagram is incomplete.
3The first stop for data leaving a device on a home network is the router, which passes it on towards the ISP		Claptop -> router -> ISP
4A path diagram for a message uses arrows to show each device the data passes through, in order, from sender to receiver		DThe path a request takes from the sender's device across the network to the server that will receive it
5device -> server -> router -> ISP		EThe devices are in the wrong order. Data from a device goes to the router, then the ISP, and only then reaches the server. The server is the last stop, not the second.
6device -> router -> ISP -> server (no reply)		Ftablet -> router -> ISP -> server

Definitions

data path

Fill in the Blanks

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

path = ["device", "______", "ISP", "server"]

device -> router -> ___ -> server

request = "device > router > ISP > server" reply = "server > ISP > router > ______"

Step 1: device sends to router Step 2: router sends to ISP Step 3: ISP sends to ______

Step 4: server sends _____ to ISP Step 5: ISP sends reply to router Step 6: router sends reply to device

Spot the Error

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

Question 1

A hop1 = "laptop"

B hop2 = "router"

C hop3 = "printer"

D hop4 = "server"

Question 2

A path = ["PC", "router", "ISP"]

B path.append("server")

C reply = path

D print(reply)

Question 3

A print("tablet to router")

B print("router to ISP")

C print("ISP to server")

D print("server to tablet")

E print("ISP to router")

F print("router to tablet")

Question 4

A message = "hello"

B path = ["PC", "ISP", "router"]

C path.append("server")

D print(message, path)

Question 5

A hops = 0

B hops += 1 # PC to router

C hops += 1 # router to ISP

D hops -= 1 # ISP to server

E print(hops)

Answer Key

Tracing data across a network

Section A: Quick Questions

A — Device, router, ISP, server

A — It passes data from your device on to the ISP

B — It travels back along the route to your device

B — False

A — The direction the data travels

Section B: Match the Pairs

device -> router -> ISP -> server → The path a request takes from the sender's device across the network to the server that will receive it

server -> ISP -> router -> device → The reply travelling back along the route to the device that sent the request

The first stop for data leaving a device on a home network is the router, which passes it on towards the ISP → laptop -> router -> ISP

A path diagram for a message uses arrows to show each device the data passes through, in order, from sender to receiver → tablet -> router -> ISP -> server

device -> server -> router -> ISP → The devices are in the wrong order. Data from a device goes to the router, then the ISP, and only then reaches the server. The server is the last stop, not the second.

device -> router -> ISP -> server (no reply) → The path only shows the data going one way. The server sends a reply that travels back along the route (server -> ISP -> router -> device), so the diagram is incomplete.

Section C: Definitions

data path — The route data takes across a network, passing through devices like a router and ISP from the sender to the receiver (a server), then the reply travels back along the route.

Section D: Fill in the Blanks

path = ["device", "router", "ISP", "server"]

device -> router -> ISP -> server

request = "device > router > ISP > server"
reply = "server > ISP > router > device"

Step 1: device sends to router
Step 2: router sends to ISP
Step 3: ISP sends to server

Step 4: server sends reply to ISP
Step 5: ISP sends reply to router
Step 6: router sends reply to device

Section E: Spot the Error

C — The third hop on the data path is the ISP, not a printer. A printer is not part of the route from the laptop to the server. It should be hop3 = "ISP".

C — The reply travels back along the route in reverse order (server, ISP, router, PC). Setting reply = path keeps the forward order. It should be reply = path[::-1].

D — The reply goes back through the same devices, so the server sends it to the ISP first, not straight to the tablet. It should be print("server to ISP").

B — Data leaves the PC and goes to the router before it reaches the ISP. The order is wrong. It should be ["PC", "router", "ISP"].

D — Each step along the path adds one hop, so the count should go up. Using -= takes a hop away. It should be hops += 1.