Subnet Sizes and Practice

Each page takes one prefix length: enter an IP address to find its network, or a larger block to list every subnet of that size. The Subnet Cheat Sheet shows every prefix from /0 to /32 with mask, wildcard and usable hosts, and Subnetting Practice makes a worksheet.

Tools in this group

• /16 Subnet Calculator — Find which /16 network an IP address is in and list every /16 block of a bigger network, with host ranges and broadcasts.
• /23 Subnet Mask (255.255.254.0) — Find which /23 network an IP address is in and list every /23 subnet of a bigger block, with host ranges and broadcasts.
• /27 Subnet Calculator — Find which /27 subnet an IP address is in and list every /27 block of a bigger network, with host ranges and broadcasts.
• /29 Subnet Mask (255.255.255.248) — Find which /29 network an IP address is in and list every /29 subnet of a bigger block, with host ranges and broadcasts.
• Subnet Cheat Sheet (Subnet Mask Chart) — Every prefix from /0 to /32 with its subnet mask, wildcard, addresses and usable hosts; highlight a row or print the chart.
• Subnetting /22 (Mask 255.255.252.0) — Find which /22 network an IP address is in and list every /22 subnet of a bigger block, with host ranges and broadcasts.
• Subnetting Practice Questions — Choose a difficulty and question type to get a subnetting worksheet; tick Show answers for the key.