[Dnsmasq-discuss] I've lost my ability to resolve local machine names without a domain suffix

Chris Green cl at isbd.net
Sun Oct 20 09:15:36 BST 2019

On Sun, Oct 20, 2019 at 08:59:03AM +0200, Geert Stappers wrote:
> On Sat, Oct 19, 2019 at 10:21:26PM +0100, Chris Green wrote:
> > 
> > So why does my laptop have *two* "search zbmc.eu" lines in
> > /etc/resolv.conf whereas other machines only have one?
> Yes, your laptop and your other machines in your network.
Only my laptop gets *two* "search zbmc.eu" lines, all the other
machines (well, all two of them that are actual accessible computers
running Linux) have only one "search zbmc.eu" which seems more

> > Also, how does this line get added to /etc/resolv.conf?
> Welcome to the wonderful world of the server-client-concept.
> The DHCP client does a "DHCP request", DHCP server (Dnsmasq) answers.
> In the reply are https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol#Client_configuration_parameters 
> such as code 15 (domain) and code 119 (domain search).
> Client uses the recieved configuration parameters (where it seems fit).
OK, yes, I supposed that must be the way it happens.  I guess for some
reason my laptop is doing something odd/wrong.  In fact I've just had
a thought, it maybe connects using WiFi sometimes and using a wired
connection at other times.  It could well be that it sends out a DHCP
broadcast request for both wired and WiFi connections.

> Check in the manual page of Dnsmasq the section "--domain". It starts
> with: "Specifies DNS domains for the DHCP server." and contains
> | In addition, when a suffix is set then hostnames without a domain part
> | have the suffix added as an optional domain part. Eg on my network I
> | can set --domain=thekelleys.org.uk and  have  a machine whose DHCP
> | hostname is "laptop". The IP address for that machine is available
> | from dnsmasq both as "laptop" and "laptop.thekelleys.org.uk".
> That gives some information about _server_ side.
I don't add any command line options to dnsmasq, my changes to the
defaults in /etc/dnsmasq.conf are as follows:-


So I have a domain= like you.  

> What happens at _client_ side, actually happens at _client_ side.
Yes, of course, and it seems to be all OK now after restarting
everything (but no other changes) so *something* had got out of kilter
so that unqualified names weren't working but was fixed by the reboots.
It may well be that upgrades (that don't usually require restarts on
Linux) had got some systemd bits in a tangle which a restart sorted out.

> > ... and why doesn't a local name only work on the machine running dnsmasq?
> Sorry, can't parse that question. If the question was
> } ... and why does a local name only work on the machine running dnsmasq?
> or 
> > ... and why doesn't a local name work on the machine running dnsmasq?
> say so.  Yes, do put effort in asking a question.[1]
Asking for the address of an unqualified name on the machine running
dnsmasq fails:-

    chris at newdns$ host esprimo
    Host esprimo not found: 3(NXDOMAIN)
    chris at newdns$ host esprimo.zbmc.eu
    esprimo.zbmc.eu has address
    chris at newdns$ 

Is there any way to fix this?  It's not incredibly impoprtant because
I only rarely do anything (as in log in and run programs) on that
machine but it would be nice if it worked the same as the other
machines on the LAN.

It's presumably down to the order in which it runs its client DHCP
requests versus when dnsmasq starts so that it can answer itself.

Thanks for all the help so far Geert.

Chris Green

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