DHCPv6 Prefix Delegation [RFC3633] allows a requesting router to include a prefix-length hint value in the IA_PD option to indicate a preference for the size of the prefix to be delegated, but is unclear about how the requesting router and delegating router should act in different situations involving the prefix-length hint. This document provides a summary of the existing problems with the prefix-length hint and guidance on what the requesting router and delegating router could do in different situations.