[Dnsmasq-discuss] dnsmasq w/Upstream DHCP

richardvoigt at gmail.com richardvoigt at gmail.com
Thu Nov 4 21:17:07 GMT 2010


These are all questions about when RedHat consults dnsmasq, not what
dnsmasq does.  It's not dnsmasq's job to "force nslookup to" anything.

You should consult resources on configuring RHEL for solutions to
these problems (for one thing, the solution is the same whether you're
running ISC Bind, dnsmasq, some other DNS service, or want to use a
different non-local DNS server than the one listed in your upstream
DHCP).

On Thu, Nov 4, 2010 at 3:21 PM, Michael Convey <smconvey at gmail.com> wrote:
> I'm using dnsmasq for small virtual network (one RHEL 5.5 machine acting as
> a Xen host - hostname: server.exampe.com - with two Xen guests). IP
> addresses of the virtual network are statically assigned and maintained in
> the /etc/host files. My /etc/hosts file reads as follows:
>
> # Do not remove the following line, or various programs
> # that require network functionality will fail.
> 127.0.0.1               localhost.localdomain localhost
> ::1                     localhost6.localdomain6 localhost6
> 192.168.122.1   server.example.com      server
> 192.168.122.2   centos.example.com      centos
> 192.168.122.3   fedora.example.com      fedora
>
> I'm not using dnsmask's DHCP functions. However, my machine is part of an
> external network that uses DHCP (Windows). Even with dnsmasq on, nslookup
> showed my system was favoring the upstream DNS servers. So, I did the
> following:
>
> 1) in /etc/sysconfig/network-scripts/ifcfg-eth0, I added the line
> "DNS1=127.0.0.1"
> 2) in /etc/dnsmasq.conf, I uncommented the line "strict-order"
> 3) in /etc/dhclient-eth0, I added the following line: supersede
> domain-search "";
>
> After a network restart, my resolv.conf file read as follows:
>
> ; generated by /sbin/dhclient-script
> nameserver 127.0.0.1
> nameserver 10.10.15.10      #upstream DNS server via DHCP
> nameserver 10.125.110.44       #upstream DNS server via DHCP
>
> Sometimes the resolv.conf spontaneously changes back to all upstream
> nameservers (drops the 127.0.0.1). If I do a network restart it comes back.
> How is the "DNS1=127.0.0.1" in /etc/sysconfig/network-scripts/ifcfg-eth0
> overridded? Could this be related to upstream DHCP lease renewal?
>
> Also, even when the resolv.conf file reads as above, 'nslookup
> server.example.com' or 'nslookup 192.168.122.1' gives the following:
>
> # nslookup 192.168.122.1
> Server:         10.10.15.10
> Address:        10.10.15.10#53
>
> ** server can't find 1.122.168.192.in-addr.arpa.: NXDOMAIN
>
> # nslookup server.example.com
> Server:         10.10.15.10
> Address:        10.10.15.10#53
>
> ** server can't find server.example.com: NXDOMAIN
>
> Why doesn't dnsmaq force nslookup to first check /etc/hosts?
>
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>



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