DHCP, Dynamic DNS, and IPv6

[Ted Lemon]

The whole point of the DUID RFC was that there was no way for a dual- 
stack client to work with DHCP and DNS updates.   There was simply no  
data reaching the server to tell it that the client was dual-stack,  
and not just two separate machines.

For legacy clients, however, it is possible to write heuristics that  
notice similarities between the DHCPv6 DUID and the DHCPv4 client- 
identifier.   I'm pretty sure you could do this for Microsoft and Mac  
OS X clients, at the very least.

Whether this is worth doing, I don't really know.   It depends on how  
quickly IPv6 gets deployed where you are.   But it's certainly possible.

Having IPv6 info overwrite IPv4 info is only useful if you have no  
dual-stack clients.   And in that case you don't really have a  
problem, because a v6-only client will be able to put its name in the  
DNS as soon as its former v4 DNS mapping expires.