A subnetting worksheet
you can make your own.
Individual IPv4 practice does not need another student account or a manually maintained spreadsheet. Set the difficulty, create one assignment link, and use student codes to generate repeatable question sets.
What belongs on an IPv4 worksheet?
A useful first task starts with a host address and prefix, then asks for six values: network address, broadcast address, subnet mask, first usable address, last usable address and number of usable hosts. This lets you see which step a learner missed.
Use conventional LAN prefixes from /8 to /30 for these questions. /31 point-to-point links and /32 host routes follow different conventions and need a separate explanation.
Worked example: 192.168.12.77/26
A /26 leaves 6 host bits. That makes 26 = 64 addresses per block. The last-octet boundaries are 0, 64, 128 and 192. The host 77 falls in the block beginning at 64 and ending at 127.
| Value | Answer | Reason |
|---|---|---|
| Network | 192.168.12.64 | Start of the containing block |
| Broadcast | 192.168.12.127 | Last address before the next block |
| Mask | 255.255.255.192 | 24 full network bits plus 2 bits |
| First host | 192.168.12.65 | Network + 1 |
| Last host | 192.168.12.126 | Broadcast − 1 |
| Usable hosts | 62 | 64 minus network and broadcast |
Run a short practice session
- Model one example and ask learners to explain the block boundary.
- Choose starter /24–/28 for first practice, mixed /20–/30 for octet transitions, or advanced /8–/30 for a wider range.
- Create 2–12 problems. Download the assignment settings as your backup.
- Share the assignment link and agree neutral student codes. Online questions match a printed variant only when the code matches exactly, ignoring capitalization and outer spaces.
- Ask students to download their answer files and return them through your existing system.
- Import files in Grade submissions. Review the skill breakdown before assigning more practice.
Keep the answer key separate
Open an assignment, enter the variant code and choose Worksheet to print the student sheet. Choose Answer key for a separate printable page. Both use the same settings and code. Your browser’s Print / Save as PDF creates a shareable file.
Common marking traps
- A learner may identify the right block size but report the original host address as the network.
- The last address in the block is the broadcast, not the last usable host.
- Count addresses before subtracting the two reserved addresses.
- A /23 changes the third octet; memorizing only fourth-octet boundaries is not enough.
Subnet Classroom recomputes each answer from the assignment and code. It does not authenticate submissions or stop a student using another calculator. Treat the results as a conversation starter for teaching, not secure exam evidence.
Free lesson packs to get started
The generator, printing, marking and downloadable lesson packs are free. Each English or Czech pack includes three original assignments, student worksheets, separate keys and a tutor guide. Download without an account or email address.
Original guide by 2059. Technical context: RFC 4632 (CIDR) and RFC 3021 (/31 exceptions). Independent of Cisco.