[pkg-dhcp-devel] Bug#823498: dhcp 4.3.1 - Random lease time is sending by servers in HA

Rafał Szymkowiak rafal.szymkowiak at inea.com.pl
Mon May 9 08:05:54 UTC 2016

I just got answer from ISC support - this behavior is correct - this is
feature, not bug - so we can close this ticket.
Here is answer from Mr. Shawn from ISC:

"There are two ways in which this can occur that are
not problems.

1) When using failover the peers will update each other
with a lease time for the a client that is in advance of
what they provide to the client.  This value is calculated
to provide the desired lease time when the client does
it's next renew.  If the client renews later than expected
the amount of time left in the calculation will be lease than
desired and that is what will be used.

2) There is a feature dhcp-cache-threshold to limit the
number of writes to the disk due to clients renewing earlier
than expected.  This feature allows the server to provide the
client with the time remaining in the current lease if the
client renews before the dhcp-cache-threshold.  By default
this is 25% so in the simple case if your clients are attempting
to renew < 3 hours after getting a 12 hour lease they will
get the remainder of the time.

You can investigate this issue by checking when a client
is renewing compared to when it was originally issued the
lease and seeing if either of these explain the behavior."

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