Hello,

i found an issue or feature request for the dyndns_update when using IPv6 Stateless Address Autoconfiguration (SLAAC) on clients and with an active dyndns_update.
I'm using a FreeIPA Server on Fedora Server 33 and some Fedora 34 and Ubuntu 20.04 Clients.
When a client gets its IPv6 address via SLAAC the address might not be configured when sssd starts and updates the DNS record,s ince the client didn't receive a IPv6 router advertisement.
As an example the default radvd configuration sends a router advertisements at a random interval (MinRtrAdvInterval/MaxRtrAdvInterval) between 198 - 600 seconds. So it can take up to 10 Minutes to get an address. In a real world scenario the interval would be lower, but the IPv6 config is usually too late for the sssd start.
So SSSD does what it should do and removes any A or AAAA records which are currently not found on the client.
Which leads to the issue, that you can't address the client via IPv6 over name resolution.
Workarounds:

• You can force the AAAA Records with a sssd service restart.
• Wait for the default 24h dyndns_refresh_interval so the client updates the records the AAAA Records, but the usual client would be already powered off.
• Set the dyndns_refresh_interval to the MinRtrAdvInterval of 198s, but that creates unnecessary load and won't scale well.

Is it possible to trigger an SSSD dyndns_update on IP change without restarting the service?