VLSM Practice Problems with Solutions — Network Design Exercises
Ten VLSM practice problems with step-by-step solutions. Practice variable length subnet masking for CCNA, CCNP, and real-world network design scenarios.
VLSM Practice Problems
Ten progressively complex VLSM design exercises with complete solutions. Suitable for CCNA exam preparation and real-world network design practice.
Problem 1 — Small office network
Given block: 192.168.10.0/24
Requirements:
- LAN-A: 100 hosts
- LAN-B: 50 hosts
- LAN-C: 20 hosts
- WAN link: 2 hosts
Solution:
Sort largest to smallest: 100, 50, 20, 2
| Subnet | Hosts needed | Prefix | Network | Range |
|---|---|---|---|---|
| LAN-A | 100 | /25 | 192.168.10.0 | .1 – .126 |
| LAN-B | 50 | /26 | 192.168.10.128 | .129 – .190 |
| LAN-C | 20 | /27 | 192.168.10.192 | .193 – .222 |
| WAN | 2 | /30 | 192.168.10.224 | .225 – .226 |
Remaining space: 192.168.10.228/30 through 192.168.10.255
Problem 2 — Branch office with multiple WAN links
Given block: 10.10.0.0/22 (1022 usable hosts)
Requirements:
- Data center LAN: 400 hosts
- Office LAN: 200 hosts
- Guest WiFi: 100 hosts
- Management: 30 hosts
- WAN-Primary: 2 hosts
- WAN-Backup: 2 hosts
Solve this using our VLSM planner and verify your answer.
Solution: Enter 10.10.0.0/22 as the parent block with the requirements above. The planner will assign /23, /24, /25, /27, /30, /30 in order.
Problems 3-10
For progressively harder exercises including IPv6 prefix delegation, hierarchical addressing, and route summarization scenarios, use the VLSM planner interactively — enter any parent block and requirement set to generate and verify solutions instantly.