My Emailiases: Re: My Emailiases: [Dnsmasq-discuss] multiple domain support - question

[L Forrister]

Simon Kelley (simon at thekelleys.org.uk) (Emailias: REPLY-MASKED) wrote:
> Original Sender:  <simon at thekelleys.org.uk>
> Given To:  lists.thekelleys.org.uk: Dnsmasq-discuss Info Page
> http://www.emailias.com/mailclick/?id=243457
> <--------------------end emailias header-------------------->
>
> L Forrister wrote:
>> Simon Kelley (simon at thekelleys.org.uk) (Emailias: REPLY-MASKED) wrote:
>>
>>> Original Sender:  <dnsmasq-discuss-bounces at lists.thekelleys.org.uk>
>>> Given To:  lists.thekelleys.org.uk: Dnsmasq-discuss Info Page
>>> http://www.emailias.com/mailclick/?id=243457
>>> <--------------------end emailias header-------------------->
>>>
>>> I have support for multiple domains working, but I've come across a 
>>> wrinkle.
>>>
>>> Consider the case that two different DHCP clients claim the same name.
>>> With the existing code, only one can have it and the current behaviour
>>> is that when a second machine  claims a name, the first one loses it.
>>>
>>> Now, consider the possibility that the two machines claiming the same
>>> name are in different domains. By default, the existing behaviour must
>>> continue, because the unqualified name is added to the DNS, so that 
>>> even
>>> though the two clients could have "name.domain1.com" and
>>> "name.domain2.com", they are still fighting over just plain "name".
>>>
>>> It would be possible to introduce a new mode, which didn't put the
>>> unqualified name into the DNS, and allowed both hosts to keep their 
>>> name
>>> as long as they are in different domains. Would that be useful, or just
>>> an confusing complication?
>>>
>>>
>>>  
>>
>>
>> I don't see anything confusing about it.  What good is multiple domain
>> support if you're forced to maintain unique host names across all 
>> domains.
>>
>>
>> I've never quite understood why dnsmasq can't allow the duplicate names
>> in the first place.  Why must it be so.  Consider a client machine 
>> with two interfaces.  Both dhcp.  They'll both get leases.  Both ip's 
>> will be active.  But the dns will only return one (name and ip) 
>> depending on which was most recently renewed.  But its not just the 
>> dns, because when you check the leases file there's only one lease 
>> listed.
>>
>
> The reason is simply that there's no way to differentiate the "plain" 
> unqualified versions of the name, without the domain part. To make the 
> multiple names work would mean suppressing unqualified names. For most 
> people, having them is more usefull that having multiple domains.
>
> Cheers,
>
> Simon.
>
As far the leases file is concerned, doesn't the mac address (and/or the
client id) provide that differentiation?   I mean, having the same
unqualified host name on two separate leases would not cause identical
lines/records in the lease file.

The dns code, seems not to have a problem with multihomed hosts in
either /etc/hosts or /etc/dnsmasq.hosts (my dnsmasq addn-hosts file.)

oso:~
lf$ dig +short -x 192.168.160.67 -x 192.168.160.68 -x 192.168.160.69
alkix.rebel.lan.
alkix.rebel.lan.
alkix.rebel.lan.

oso:~
lf$ dig +short alkix.rebel.lan
192.168.160.67
192.168.160.68
192.168.160.69

~~L.Forrister