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Re: DNS problem on local network



On Thu, 9 Aug 2007, Adam Hardy wrote:

Jeff D on 09/08/07 00:55, wrote:
On Thu, 9 Aug 2007, Adam Hardy wrote:
Jeff D on 08/08/07 00:34, wrote:
On Tue, 7 Aug 2007, Adam Hardy wrote:
debian@reinketelaars.nl on 06/08/07 21:04, wrote:
My server isengard runs dnsmasq to provide the dhcp clients. However it
doesn't recognise any internal network domain name:

isengard:~# hostname
isengard
isengard:~# hostname --fqdn
hostname: Unknown host
isengard:~# nslookup gondor
Server:         194.74.65.69
Address:        194.74.65.69#53

** server can't find gondor: NXDOMAIN

I worked out the domain name should go into /etc/resolv.conf (
http://www.tldp.org/HOWTO/NET3-4-HOWTO-5.html ) but then it seems that
this is under the control of something else.

The domain name should go into /etc/resolv.conf
You also have to assign the first nameserver to be _your_ nameserver and not your ISP's.

# cat /etc/resolv.conf
search isengard.net
nameserver 127.0.0.1
nameserver ...
nameserver ...

Something is rewriting my resolv.conf at least every minute. I suspected it must be dnsmasq attempting to do the DNS but I just stopped dnsmasq, and yet resolv.conf is still being updated. I had a look over my ps output but dont see anything that could be controlling resolv.conf.

This is the only entry in it:

nameserver 194.74.65.69

which is the British Telecom DNS.

Do you have the resolvconf package installed?

No. That looks like a culprit, but no. Not installed.

Checking out the dhclient3 and dhclient.conf man pages, it makes no reference to resolv.conf but it does claim to be able to do dynamic DNS updates.

I would have to try disabling the dhclient3 NIC to test if it is this program rewriting resolv.conf, but i have to wait until the others using the net have finished.

How exactly would I set the domain name on the machine - the name I thought I'd chosen when setting up the system from CD?

At the moment on this machine when I run 'hostname --domain' it returns nothing.

to set the domain name, add it into /etc/hosts, for example:
127.0.0.1       localhost
127.0.1.1       mybox.mynet.net        mybox

in /etc/hostname :
mybox

at start up /etc/init.d/hostname.sh runs, parses these and comes up the domain name.

to turn off dhcp provided /etc/host info, edit /etc/dhcp3/dhclient.conf, there is a line that starts with request. Remove domain-name-servers from that list and dhcp wont supply it. If you read down further, you can supply your own through the option variables.

for more dhcpclient goodness  man dhclient.conf

Yes I tried to work out what was going on by reading the man pages, but I didn't find it so illuminating. My problem is that the DHCP and DNS server running dnsmasq is actually the gateway server and has a second NIC connected to a modem, from which it gets its ip via DHCP, hence the reason why this box is running dnsmasq for one NIC and dhclient3 for the other.

It is the resolv.conf on this machine that is being rewritten constantly by something.

In that context, do those instructions for setting the domain name on the machine still hold? It slightly throws me that you quote the ip address 127.0.1.1


Thanks
Adam

You can put your IP in /etc/hosts as:
192.168.1.150   mybox.mynet.net mybox

i just had 127.0.0.1 in mine, sorry for the confusion on that.

This machine also gets its network info through dhcp, which also over writes /etc/resolv.conf. If you want to keep certian info in there , like a search domain and specify a namserver, add to /etc/dhcp3/dhclient.conf :
supersede domain-name "mynet.net mynet.local";
prepend domain-name-servers 127.0.0.1;

then, /etc/init.d/networking restart

and you should see in /etc/resolv.conf:
search mynet.net mynet.local
nameserver 127.0.0.1
nameserver 192.168.1.10

you will still need to have your ISPs dns server listed in /etc/resolv.conf , as dnsmasq uses that as its name server.

then, you can add in hosts into /etc/hosts , restart dnsmasq and it will reread /etc/resolv.conf and /etc/hosts

I hope that clears up things a little.

Jeff

-+-
8 out of 10 Owners who Expressed a Preference said Their Cats Preferred Techno.



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