2317: Classless IN-ADDR.ARPA delegation.

This document describes a way to do IN-ADDR.ARPA delegation on non- octet boundaries for address spaces covering fewer than 256 addresses. The proposed method should thus remove one of the objections to subnet on non-octet boundaries but perhaps more significantly, make it possible to assign IP address space in smaller chunks than 24-bit prefixes, without losing the ability to delegate authority for the corresponding IN-ADDR.ARPA mappings. The proposed method is fully compatible with the original DNS lookup mechanisms specified in [1], i.e. there is no need to modify the lookup algorithm used, and there should be no need to modify any software which does DNS lookups.