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IPv4 Subnetting Made Simple: A /26 Worked Example

Understand network and broadcast addresses, host ranges and usable hosts using the concrete example 192.168.10.0/26.

Subnetting questions become simpler when you treat the prefix as a count of network bits and work in blocks. We will use the private network 192.168.10.0/26 to show the mask, block size, valid host range and a quick method for checking answers.

Translate the prefix into a mask

An IPv4 address contains 32 bits. A /26 prefix uses 26 bits for the network and leaves 6 for the host portion. The subnet mask is 255.255.255.192 because the last octet has two network bits set: binary 11000000.

Six host bits create 2^6 = 64 total addresses in each /26 block. In a typical subnet, the network address and broadcast address are not assigned to ordinary hosts, leaving 62 usable host addresses.

Find the range of the first subnet

The fourth-octet block size is 256 minus 192, which equals 64. The /26 ranges therefore begin at .0, .64, .128 and .192 within the same /24.

For 192.168.10.0/26, the network address is 192.168.10.0. The broadcast address is 192.168.10.63. Usable host addresses run from 192.168.10.1 to 192.168.10.62.

  • Prefix: /26
  • Mask: 255.255.255.192
  • Addresses per subnet: 64
  • Typical usable hosts: 62
  • First block: 192.168.10.0–192.168.10.63

Check a host address in the next block

Consider 192.168.10.70/26. Because 70 lies between 64 and 127, its subnet is 192.168.10.64/26, and the broadcast address is 192.168.10.127.

The usable range is 192.168.10.65 through 192.168.10.126. To check your answer, verify that your network and broadcast addresses align with a 64-address block.

Practise without memorising a table

Try 192.168.10.150/26. Its block begins at 128; the network is 192.168.10.128 and the broadcast is 192.168.10.191. The typical usable range is .129–.190.

This worked example assumes conventional IPv4 subnet use. Special cases such as /31 point-to-point links have different addressing conventions. Learn the bit reasoning rather than using a rule blindly for every prefix.

Quick checklist

  • I can explain why /26 leaves six host bits.
  • I can convert /26 to 255.255.255.192.
  • I calculate the block size from the mask.
  • I identify network and broadcast addresses correctly.
  • I distinguish total addresses from typical usable hosts.
  • I verify the answer with a second example.

Always confirm current syllabus, coursework and assessment rules with your institute or lecturer.