DDNS update not sent on initial DHCP offer/request/ack

[/dev/rob0]

On Wed, Dec 07, 2016 at 10:33:02AM -0500, Forman, Jeffrey wrote:
> I've got a fairly standard setup here, ISC dhcpd handing out IPv4 
> address, updating a DNS zone handled by BIND with those hostnames. 
> Though it seems lately (perhaps it's always been this case?) that 
> the first time a new host comes up and requests an IP from the dhcp 
> server, BIND is not notified of the new hostname and IP address. I 
> have to reboot the client and then, on the subsequent request/ack 
> cycle, is DNS updated. So my question is, why do I have to reboot 
> the clients to get dhcpd to update bind? Is something misconfigured 
> in my DHCPD to not do the intial update, or is it something 
> client-side that is needed?

What you showed us suggests it's a client issue.

> Infrastructure:
> 
>    - dhcp server os: OpenBSD 6.0 on amd64 ($OPENBSD in the below logs)
>    - dhcpd version: isc dhcpd 4.3.4
>    - bind version: isc bind 9.10-4p2
>    - client OS: CoreOS (though I also run ubuntu and OSX locally as well)
>    ($COREOSCLIENT in the below logs)
> 
> From the DHCPD logs, the initial request:
> 
> Dec  7 06:25:49 $OPENBSD dhcpd: DHCPOFFER on 10.10.2.245 to
> 52:54:00:18:f7:fb via vlan12
> 
> Dec  7 06:25:49 $OPENBSD dhcpd: DHCPREQUEST for 10.10.2.245 (10.10.2.1)
> from 52:54:00:18:f7:fb via vlan12
> 
> Dec  7 06:25:49 $OPENBSD dhcpd: DHCPACK on 10.10.2.245 to 52:54:00:18:f7:fb
> via vlan12

I don't see in that where any hostname was provided.

> I reboot the client, and then:
> 
> Dec  7 06:27:59 $OPENBSD dhcpd: DHCPREQUEST for 10.10.2.245 (10.10.2.1)
> from 52:54:00:18:f7:fb via vlan12
> 
> Dec  7 06:27:59 $OPENBSD dhcpd: DHCPACK on 10.10.2.245 to 52:54:00:18:f7:fb
> (coreE3) via vlan12

Here "coreE3" is the hostname ... was this a munging failure meant to 
be "$COREOSCLIENT"?

> 07-Dec-2016 06:27:59.177 update-security: info: client 10.10.2.1#28804/key
> $TSIG-KEY: signer "$TSIG-KEY" approved
> 
> 07-Dec-2016 06:27:59.177 update: info: client 10.10.2.1#28804/key
> $TSIG-KEY: updating zone 'dns.zone.net/IN': adding an RR at '$COREOSCLIENT'
> A 10.10.2.245

"Zone.net" is not a good choice for a home zone name.  If you're 
simply hiding the real name behind "zone.net", use "example.net" 
which has been set aside for such use.

[snip]
> What am I missing here? Why does it require a restart of the client 
> to get the dns entry added?

Apparently it did not provide a hostname to add to DNS.
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