[Kea-users] Getting Started: Dual-stack Dynamic DNS Updates

[Troy Telford]

I’ve been successful so far in getting Kea to serve IPv4 with both forward & reverse dynamic DNS. Thus far I’ve only used SLAAC and static zone files for IPv6 in DNS in my test/educational network. (A small network, so I can learn & experiment).

I’ve had a notion of also learning DHCPv6 so I know how it works. (I’ve a goal to understand and have dual stack DHCP with forward/reverse DNS updates).

It’s already clear it’s different from IPv4 DHCP. I’ve been able to piece together a rough idea of some basics - enough that there are signs of life: I configured `radvd` with the correct flags so macOS & iOS use DHCPv6, for example. it seems many of the hosts are getting IPv6 addresses from Kea-dhcp6, though it’s equally clear I’m missing important details, as things aren’t working as I’d thought: 

In this dual-stack environment, it seems kea-dhcp-ddns is sort of all over the place: I’m seeing either IPv4 updates, or IPv6 updates, but not both in DNS.

I want to make sure I understand the situation properly before getting lost in the weeds (ie. Trying to ‘fix’ the wrong thing): 

   * Is it true that in a dual-stack environment, it’s necessary for the _client_ to be configured properly in order for `kea-dhcp-ddns` to be able to update the DNS server properly?
       * I’ve read that both v4 and v6 clients need to send the same DUID for ddns to work properly - is that correct?
       * Am I wrong that most Linux distributions, and macOS aren’t configured this way by default? (I haven’t checked Windows yet…)
       * I’m sure there are minutae I need to learn - any hints?
   * While I don’t _think_ I’m running into any unimplemented functionality, is there something I should be aware of for the simple goal of dual-stack forward/reverse dynamic DNS? - (I’m using kea-2.2.0 on Debian Sid because I’ve apparently 'lived dangerously' for 25 years.)

I’ve also noticed that many hosts are getting “new” IPv6 addresses that are from a subnet that’s not link-local (I think), and _not_ the subnet that I’m assigning via DHCPv6: fd75:81b2:5386:4f06::/64.

* I think it’s something akin to the 169.254 IPv4 address range, but my Google-fu fails me; is there anything special about such a subnet? Why would the interfaces be getting such an address?

Thank you.