Private and public IP addresses
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Which address is a private IP address?
2. Which statement about a public IP address is correct?
3. Which address falls inside a private range?
4. Ten devices in your house are online. How many public IP addresses does your home network usually need?
5. What does NAT (network address translation) do?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1192.168.1.5 | ANAT: 192.168.1.5 -> 203.0.113.8 | |
| 210.0.0.12 | B172.20.4.9 | |
| 3The router uses NAT so many devices on a home network can share one public IP address | CA private IP address that works only inside a local network such as a home Wi-Fi network | |
| 4The private range from 172.16 to 172.31 is reserved for local networks only | D192.168.0.20 is a private address that only works inside a local network, so it cannot be used to reach a server on the internet. | |
| 5Each phone and laptop at home has its own public IP address, so the internet sees 192.168.1.5 | E192.168.1.5 is a private address, so the internet cannot see it. The internet sees only the router's public IP address. | |
| 6A web server on the internet is reached using the address 192.168.0.20 | FA private IP address from the 10.x.x.x range, often used in schools and large organisations |
C
Definitions
private IP address
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
192.168.1.5 is a _______ IP address
2.
Private range: __.0.0.0 to 10.255.255.255
3.
Private range: 172.__.0.0 to 172.31.255.255
4.
The router uses ___ to translate addresses
5.
Laptop: 192.168.1.5 (private)
Router: 203.0.113.7 (______)
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
laptop = "192.168.1.5"
B
kind = "public"
C
print(kind)
Question 2
A
lan_range = "10.0.0.0/8"
B
home_range = "192.168.0.0/16"
C
mid_range = "172.60.0.0/12"
Question 3
A
router_public = "203.0.113.9"
B
pc_private = "192.168.1.10"
C
nat_job = "block all traffic"
Question 4
A
devices = 5
B
public_ips_needed = devices
C
# NAT shares one public IP
Question 5
A
src = "192.168.1.5"
B
dest = "93.184.216.34"
C
# router applies NAT
D
src = "192.168.1.5"
Answer Key
Private and public IP addresses
Section A: Quick Questions
Q1
B — 192.168.1.5
Q2
A — It is the address the internet sees for your network
Q3
A — 172.20.4.9
Q4
A — One, shared by all the devices
Q5
B — Translates between private and public addresses
Section B: Match the Pairs
Q1
192.168.1.5 → A private IP address that works only inside a local network such as a home Wi-Fi network
Q2
10.0.0.12 → A private IP address from the 10.x.x.x range, often used in schools and large organisations
Q3
The router uses NAT so many devices on a home network can share one public IP address → NAT: 192.168.1.5 -> 203.0.113.8
Q4
The private range from 172.16 to 172.31 is reserved for local networks only → 172.20.4.9
Q5
Each phone and laptop at home has its own public IP address, so the internet sees 192.168.1.5 → 192.168.1.5 is a private address, so the internet cannot see it. The internet sees only the router's public IP address.
Q6
A web server on the internet is reached using the address 192.168.0.20 → 192.168.0.20 is a private address that only works inside a local network, so it cannot be used to reach a server on the internet.
Section C: Definitions
Q1
private IP address — An address like 192.168.1.5 that works only inside a local network. The internet sees the router's public IP instead, and NAT translates between the two so many devices can share it.Section D: Fill in the Blanks
Q1
192.168.1.5 is a private IP addressQ2
Private range: 10.0.0.0 to 10.255.255.255Q3
Private range: 172.16.0.0 to 172.31.255.255Q4
The router uses NAT to translate addressesQ5
Laptop: 192.168.1.5 (private)
Router: 203.0.113.7 (public)Section E: Spot the Error
Q1
B — Addresses starting 192.168 are in a private range, so the laptop's address is private. The line should be kind = "private".
Q2
C — The private range runs from 172.16 to 172.31, so 172.60 is not private. It should be "172.16.0.0/12".
Q3
C — NAT does not block traffic. It translates between private and public addresses, so it should be "translate addresses".
Q4
B — NAT lets many devices share one public address, so the home only needs 1 public IP, not one per device.
Q5
D — After NAT, the router swaps the private source address for its own public address. Line 4 should be src = "203.0.113.9".