NAMED: annoying error in syslog

[Kevin Darcy]

Alessandro FAGLIA wrote:
> Hi list.
> I managed in having DHCP and BIND interacting in order to update zone 
> files as soon as a lease is released.
>
> Everything works fine, but I have an annoying (it's just my point of 
> view) message in /var/log/syslog, where dhcpd and named are logging.
> Here is what I see:
>   
>> Aug 27 09:34:06 cnsrv010 dhcpd: DHCPDISCOVER from 00:11:d8:ec:cc:f9 
>> via bond0: network 192.168.1/24: no free leases
>> Aug 27 09:34:06 cnsrv010 dhcpd: DHCPDISCOVER from 00:11:d8:ec:cc:f9 
>> via bond1
>> Aug 27 09:34:06 cnsrv010 dhcpd: DHCPOFFER on 192.168.2.29 to 
>> 00:11:d8:ec:cc:f9 via bond1
>> Aug 27 09:34:06 cnsrv010 dhcpd: DHCPREQUEST for 192.168.2.29 
>> (192.168.2.1) from 00:11:d8:ec:cc:f9 via bond0: wrong network.
>> Aug 27 09:34:06 cnsrv010 dhcpd: DHCPNAK on 192.168.2.29 to 
>> 00:11:d8:ec:cc:f9 via bond0
>> Aug 27 09:34:06 cnsrv010 named[13071]: client 127.0.0.1#32869: 
>> updating zone 'mydomain.it/IN': update unsuccessful: CNWKS2K034
>> .mydomain.it: 'name not in use' prerequisite not satisfied (YXDOMAIN)
>> Aug 27 09:34:06 cnsrv010 named[13071]: client 127.0.0.1#32869: 
>> updating zone 'mydomain.it/IN': deleting rrset at 
>> 'CNWKS2K034.mydomain.it' A
>> Aug 27 09:34:06 cnsrv010 named[13071]: client 127.0.0.1#32869: 
>> updating zone 'mydomain.it/IN': adding an RR at 'CNWKS2K034.mydomain.it' A
>> Aug 27 09:34:06 cnsrv010 dhcpd: Added new forward map from 
>> CNWKS2K034.mydomain.it to 192.168.2.29
>> Aug 27 09:34:06 cnsrv010 named[13071]: client 127.0.0.1#32869: 
>> updating zone '168.192.in-addr.arpa/IN': deleting rrset at '2
>> 9.2.168.192.in-addr.arpa' PTR
>> Aug 27 09:34:06 cnsrv010 named[13071]: client 127.0.0.1#32869: 
>> updating zone '168.192.in-addr.arpa/IN': adding an RR at '29.
>> 2.168.192.in-addr.arpa' PTR
>> Aug 27 09:34:06 cnsrv010 dhcpd: added reverse map from 
>> 29.2.168.192.in-addr.arpa. to CNWKS2K034.mydomain.it
>>     
> The annoying line is:
>   
>> Aug 27 09:34:06 cnsrv010 named[13071]: client 127.0.0.1#32869: 
>> updating zone 'farmol.it/IN': update unsuccessful: CNWKS2K034
>> .mydomain.it: 'name not in use' prerequisite not satisfied (YXDOMAIN)
>>     
> I'd like to know the meaning of this message, if this is just a normal 
> log or is due to a configuration error.
> BTW, the host CNWKS2K034 is already listed in the zone file before named 
> tries to do its job.
>
>   
Looks normal to me. The initial request basically consists of "add the 
record if it doesn't already exist". The record already exists so the 
update "fails". DHCPD detects the "failure" and thus follows up with a 
"delete" followed by an "add". The end result is the same.

The only question in my mind is: why did the record already exist? If 
DHCPD has complete control over the entry, in theory it should have 
deleted it when the lease expired or was relinquished by the client. 
But, in practice, I know that there are many variables involved, e.g. 
maybe the client was powered off ungracefully and didn't have time to 
issue a DHCPRELEASE. There are many other possibilities, all of which 
fall within the range of "normal"...
                                                                         
                 
                                                                        
    - Kevin