Microsoft There has been recently a lot of the discussion in the IPNG, NGTRANS and DNSEXT working group about the level at which IPv6 shall support renumbering. A specific question is whether we need special support in the DNS to enable renumbering, as specified in [RFC2874], or if the simpler mechanisms specified in [RFC1886] are sufficient. In order to organize the discussion, this memo presents a set of realistic renumbering scenarios, discusses the possible frequency at which such scenarios can be repeated, presents some tools that can be used to organize the renumbering, and summarizes the operational requirements that have to be met by any renumbering solution.