Help with /etc/resolv.conf updates - dnsmasq

[Carthik Sharma]

On 7/9/06, Matthew Kuiken <matt.kuiken at verizon.net> wrote:
> Carthik Sharma wrote:
> >
> > As an aside, how often do the NS ip addresses for an ISP change? If
> > they don't change, ever, then I will be good by creating a copy of my
> > current resolv.conf and pointing dnsmasq to the copy for non-cached NS
> > lookups.
> >
> > I am sorry if some of the above is unclear - please ask and I will
> > explain what I mean, if that is the case.
>
> It wasn't entirely clear, but I think I understood.  I can't help with
> your main question, but in regards to the NS addresses for your ISP, I
> have an opinion.
>
> I don't believe that name servers change IP addresses very often.
> Mainly because of the amount of time the change would take to propagate
> through the network, and the difficulty of dealing with customer calls
> when the DNS stops working for them.  I have not ever noticed that my
> ISP's name servers changed addresses.  I don't watch them all that
> closely either though.  If they do change, I would think that it would
> be such an infrequent change that manual updating of your configuration
> file would not be a real issue.

That's what I thought, and so I will just create a copy of resolv.conf
for dnsmasq to use for remote NS lookups.

> Hmm, now that I look at it, this really doesn't answer anything, as it
> just presents my opinion, and does not help you with the overwrite of
> resolve.conf by the DHCP lookup.  I'm sorry that I really can't be of
> more concrete help.

I will lookup the dhclient.conf file to see if there is an easy way to
circumvent the over writing of the resolv.conf file. I suppose
uncommenting the "#  option domain-name-servers 127.0.0.1;" line is
all htat will be required.

My original question was, how do I get dhcp3 client to write the new
NS IP addresses to a file other than resolv.conf whenever it does
write new values? There, I think I got it right the second time around
:)

Also, if I have say:
127.0.0.1
xxx.xxx.xxx.xxx
yyy.yyy.yyy.yyy

in my /etc/resolv.conf will dnsmasq just use the entries in that
order, without any problems? I suppose by default, local resolve
requests will be handled by dnsmasq, and when not possible, dnsmasq
will lookup from an upstream NS (the xxx and yyy entries)? I am afraid
this might put things in an infinite loop though - any knowledgeable
opinions would be welcome.

Thanks,
Carthik.
> -Matt
>
>
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-- 
Ph.D. Candidate
University of Central Florida
Homepage: http://carthik.net