[Dnsmasq-discuss] DNS vs dhcp-script

Ferenc Wagner wferi at niif.hu
Wed Sep 15 19:46:43 BST 2010

Simon Kelley <simon at thekelleys.org.uk> writes:

> Ferenc Wagner wrote:
>> Is the a way to ensure that the dhcp-script can resolve the newly issued
>> lease?  (Of course it isn't a problem for the script itself, but for a
>> stubborn program started from it, which does two-way DNS resolution just
>> to make sure.)  It seems to be racy, sometimes it works, sometimes it
>> does not...  I think the script invocation should be moved after
>> registering the new lease in the DNS database.  Or maybe the problem is
>> something else entirely.
> Quickly checking the code, the DNS system gets updated long before the
> script could possibly be run. "Something else entirely" looks a distinct
> possibility.

Yeah, the following log excerpt shows that the dhcp-script called
new_sge_client could resolve perfectly well, but another
program (qconf from SGE) called from it later failed that (last, tagless
line) without even making a query:

dnsmasq-dhcp: DHCPDISCOVER(br-alma-g) 52:54:00:12:34:56
dnsmasq-dhcp: DHCPOFFER(br-alma-g) 52:54:00:12:34:56
dnsmasq-dhcp: DHCPREQUEST(br-alma-g) 52:54:00:12:34:56
dnsmasq-dhcp: DHCPACK(br-alma-g) 52:54:00:12:34:56 52-54-00-12-34-56
new_sge_client: root: del 52:54:00:12:34:56 52-54-00-12-34-56
new_sge_client: root: add 52:54:00:12:34:56 52-54-00-12-34-56
dnsmasq: query[PTR] from
dnsmasq: DHCP is 52-54-00-12-34-56.alma.grid
new_sge_client:     52-54-00-12-34-56.alma.grid
unable to resolve host ""

I'm stumped.  Maybe it's time to pull out the big-hammer strace...

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