dhcpd losing hostnames

Michael Vincent vyncebox at gmail.com
Fri Jul 15 04:21:34 UTC 2016

On Wed, Jul 13, 2016 at 1:31 AM, Michael Vincent <vyncebox at gmail.com> wrote:
> On Tue, Jul 12, 2016 at 2:57 PM, Shawn Routhier <sar at isc.org> wrote:
>> You can try to disable it by setting it to 0, add the following line in your config:
>> dhcp-cache-threshold 0;
>> and see if that affects the problem.
> Thanks, I'll give that a shot!

Setting dhcp-cache-threshold to 0 has completely resolved the issue
for two of us on three installations so far :-). That works great as a
workaround, but it would be nice to fix the root issue.

I've looked at the source a bit, but don't understand the whole flow
yet. Do you have any idea why isc-dhcpd might forget the client
hostname in the reuse_lease case? The section of code around
server/dhcp.c:3037 looks like it should handle populating
lt->client_hostname, but perhaps that's failing for some reason? Since
lt->cltt is getting updated, it seems unlikely that the new lease is
getting entirely lost or erased.

I got the unit tests building and running, but I don't see any
high-level tests that I could modify to reproduce this issue.

What are the next steps?

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