The following is mostly taken from http://tools.ietf.org/html/rfc2317 but it is so good I wanted to share it here. Basically this allows for DNS delegation of the reverse zone for address spaces covering fewer than 256 addresses. Let us assume we have assigned the address spaces to three different parties as follows:
192.0.2.0/25 to organization A 192.0.2.128/26 to organization B 192.0.2 …