Allow absolute values for DDNS RR TTLs (to correctly meet RFC 4702, Section 5)
We are currently preparing a migration from dhcpd
to Kea and are struggling a bit with DNS TTLs for DDNS entries created with Kea. We have a requirement from the organisation to have our default lease time be 2 days
/ 172800 seconds
, but in combination with a short TTL of 300 seconds
because our Juniper firewall rules are almost entirely name based.
Since Kea only calculates the TTL we are currently having to set ddns-ttl-percent
to .00174
to get a 301 second
TTL. However since we are setting this globally, the result is that any client classes where we explicitly want much shorter lease than the default to get a 1 second
TTL.
RFC 4702, Section 5 does also mention that TTLs should also be configurable as an absolute time interval:
We recognize that individual administrators will have varying requirements: DHCP servers and clients SHOULD allow administrators to configure TTLs and upper and lower bounds on the TTL values, either as an absolute time interval or as a percentage of the lease time.
This is something that would be ideal for us and hopefully useful for others. I hope it can be considered.
Thank you to the Kea devs and ISC for all your hard work