[Dnsmasq-discuss] Dnsmasq dns/dhcp with multiple subnet - lease file issue

[Simon Kelley]

On 09/09/13 14:07, Robert Tsai wrote:
> Hi Simon,
>
> Thanks for the reply!  Sorry I didn't clarify,  each subnet is on its
> own nic on  the dnsmasq server.   The storage subnet is an isolate
> non-routed network.  So the storage subnet clients do get a ip from
> dhcp but the mac, lease, and hostname never get populated to the
> dnsmasq.leases file only the app subnet clients do.  Btw, my current
> dnsmasq server is on ver 2.48 on centos6.3.

I understand. If the storage subnet clients get a DHCP lease, but the 
leases never appear in dnsmasq.leases file, then they may well be 
getting a DHCP lease from another DHCP server on that network. You 
really need to check the logs to see if the clients are talking to 
dnsmasq, or another DHCP server that's there accidentally.
>
> As for dhclient sending host name, is it possible to have, for
> example, a subdomin added to the hostname?  I tried to send node.str
> but dnmasq ignores anything after node\.  Again really appreciate the
> help!


Check the --domain dnsmasq config option - you can associate domains 
with subnets.


Cheers,

Simon.

>
> Robert
>
>
>
> Sent from my iPhone
>
> On Sep 9, 2013, at 3:33 AM, Simon Kelley<simon at thekelleys.org.uk>
> wrote:
>
>> On 08/09/13 14:09, Robert Tsai wrote:
>>>
>>> Hi,
>>>
>>> I am having issues with dnsmasq with dns/dhcp with multple
>>> subnets. I have two subnets , one named app and the other
>>> storage.  Both subnet clients get ips through dhcp but only the
>>> app subnet client's lease gets propagated to
>>> /var/lib/dnsmasq.leases.  The storage subnet client's lease never
>>> gets written to that file.
>>
>> I'm assuming that both subnets are on the same physical network
>> adapator.
>>
>> A client (as identified by MAC address) can't have two leases at
>> once. My guess is that the first lease achieved is on the storage
>> subnet, and that gets deleted when the same client gets another
>> lease. It's worth looking in the system log to see what happening,
>> and also worth setting --log-dhcp to get more information there.
>>
>> One way around this is to configure the DHCP clients to send
>> different client-IDs for the two subnets, they'll be treated as two
>> different leases for two different clients.
>>
>> Also if I have a
>>> client server that needs to have both subnets and sends its
>>> host-name from dhclient, will dnsmasq add both host-name to the
>>> lease file? Any help on this would be appreciated.  Below are the
>>> options that are set for dhcp and dns.
>>
>> No. A hostname is only ever associated with one DHCP lease.
>>
>>
>> Cheers,
>>
>> Simon.
>>
>>> Thanks, Robert
>>>
>>> addn-hosts=/etc/dnsmasq.d/dhcp_qa_hosts bogus-priv
>>> domain=app.domain.net,10.10.123.201,10.10.123.240
>>> domain=str.domain.net,10.10.133.201,10.10.133.240 domain-needed
>>> expand-hosts log-dhcp
>>>
>>> log-queries dhcp-option=option:dns-server,10.10.123.5
>>> dhcp-range=app,10.10.123.201,10.10.123.240,12h,app.domain.net
>>> dhcp-option=net:app,121,10.10.120.0/24,10.10.123.241,10.10.121.0/24,10.10.123.241
>>
>>>
dhcp-range=storage,10.10.133.201,10.10.133.240,12h,str.domain.net
>>> dhcp-option=net:storage,3
>>> dhcp-option=net:storage,121,10.10.130.0/24,10.10.133.241
>>> dhcp-option=net:app,option:router,10.10.123.
>>>
>>>
>>>
>>> _______________________________________________ Dnsmasq-discuss
>>> mailing list Dnsmasq-discuss at lists.thekelleys.org.uk
>>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>>
>>
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>