You have four networks of,, and you need to supernet in order to use once ACL in a firewall. – fall into the range of – which consists of a 32 decimal division.

The first octets are 255.255, to calculate the 3rd octet we need to covert 32 decimal to a binary bit mask:


2^5 = 32. As we are working on the subnet we work from the left. The resulting mask is 11100000.

The third octet now has 3 bits making the CIDR 8 + 8 + 3 = 19.

The subnets will be as follows: - - -

The final address will be

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