[Dnsmasq-discuss] dnsmasq w/Upstream DHCP

Michael Convey smconvey at gmail.com
Thu Nov 4 20:21:23 GMT 2010


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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