Subnetting is a skill and like all skills, it improves with practice. This section contains a collection of exercises designed to test your understanding of subnet masks, FLSM (Fixed Length Subnet Masking), and VLSM (Variable Length Subnet Masking).
Each exercise includes a specific network requirement and asks you to plan and calculate the appropriate subnets. No solutions are provided you’ll need to think them through and verify your answers.
| ID | Complexity | Needed / Requirements | Type | Link |
|---|---|---|---|---|
| 1 | Easy | Divide 192.168.10.0/24 into 4 equal subnets | FLSM | Exercise 1 |
| 2 | Easy | Create 8 subnets for 8 departments from 10.0.0.0/24 | FLSM | Exercise 2 |
| 3 | Medium | A company needs subnets for 30, 20, 10, and 2 hosts | VLSM | Exercise 3 |
| 4 | Medium | You have 172.16.0.0/16 and need 10 subnets of 500 hosts each | FLSM | Exercise 4 |
| 5 | Medium | Design subnets for a branch office needing 3 networks: 60, 25, and 10 hosts | VLSM | Exercise 5 |
| 6 | Hard | Given 192.168.100.0/24, plan subnets for 6 departments with 100, 50, 25, 10, 5, and 2 hosts | VLSM | Exercise 6 |
| 7 | Hard | Subnet 10.1.0.0/16 to create 20 subnets with at least 2000 hosts each | FLSM | Exercise 7 |
| 8 | Hard | From 192.168.0.0/22, create subnets for departments needing 100, 50, 30, and 10 hosts | VLSM | Exercise 8 |
| 9 | Expert | You manage an ISP block 203.0.113.0/24 allocate subnets for 4 clients with 80, 40, 20, and 10 hosts | VLSM | Exercise 9 |
| 10 | Expert | From 172.20.0.0/20, design a VLSM plan for a campus with varying host sizes (500, 300, 200, 100, 50) | VLSM | Exercise 10 |
Network: 192.168.10.0/24
Goal: Divide the network into 4 equal subnets.
Type: FLSM
Hint: Each subnet must have the same number of hosts.
Network: 10.0.0.0/24
Goal: Create 8 subnets, one for each department.
Type: FLSM
Hint: Focus on how many bits you need to borrow to create 8 subnets.
Scenario: A company requires subnets for departments with 30, 20, 10, and 2 hosts.
Base Network: 192.168.50.0/24
Type: VLSM
Hint: Start with the largest subnet and allocate downward.
Network: 172.16.0.0/16
Goal: Create 10 subnets, each supporting at least 500 hosts.
Type: FLSM
Hint: Determine how many host bits to reserve for 500 usable IPs.
Scenario: A branch office needs 3 subnets supporting 60, 25, and 10 hosts.
Base Network: 10.10.10.0/24
Type: VLSM
Hint: Optimize address usage avoid wasting IPs on smaller networks.
Scenario: You’re given 192.168.100.0/24 and need to create subnets for 100, 50, 25, 10, 5, and 2 hosts.
Type: VLSM
Hint: Remember each subnet must have at least 2 addresses reserved for network and broadcast.
Network: 10.1.0.0/16
Goal: Create 20 subnets, each capable of supporting at least 2000 hosts.
Type: FLSM
Hint: Think about how many bits to borrow from the host portion.
Network: 192.168.0.0/22
Goal: Create subnets for departments needing 100, 50, 30, and 10 hosts.
Type: VLSM
Hint: Try fitting these subnets efficiently into the /22 range without overlaps.
Scenario: You manage an ISP block 203.0.113.0/24.
Goal: Allocate subnets for 4 clients needing 80, 40, 20, and 10 hosts.
Type: VLSM
Hint: Work top-down assign from the largest client to the smallest.
Scenario: A campus network uses 172.20.0.0/20.
Goal: Design a VLSM plan for five departments needing 500, 300, 200, 100, and 50 hosts.
Type: VLSM
Hint: Efficiently distribute the address space; minimize wasted IPs.
Happy subnetting may your CIDR blocks be ever efficient!