Calculate the network boundary before scanning a range of addresses. CIDR notation is used to identify addresses within the same subnet and reduce unnecessary scanning.

Basic approach

IPv4 address is 32 bits; The number after the slash indicates the length of the network prefix. /24 contains a total of 256 addresses, /26 contains a total of 64 addresses. In traditional broadcast-supported subnets, network and broadcast addresses are not given to the client. /31 point-to-point connections and /32 individual routes are excluded from this simple subtraction rule.

Application steps

  1. Record the address and mask of the active adapter; Do not accidentally use the VPN adapter's information.
  2. Calculate the network address, end address, and total number of addresses using the prefix.
  3. Limit the scan target to the network within your management scope; Check the results with a known device first.

Practical example

192.168.10.70/26 is at block 192.168.10.64–127. The traditional client range would be .65–.126. Selecting 192.168.10.0/24 covers three different blocks; You may not have access to these blocks.

Interpret the result correctly

Addresses that look similar are not necessarily on the same subnet. Mask change is not a method of discovery; The wrong mask can disrupt communication. Verify the calculation, do not change working network settings just for scanning.

Source and follow-up reading

Protocol or command details: RFC 4632. The steps and example scenario are IPScans editorial narrative.