Does dnsmasq select any DNS server on lan?

Installing and Using OpenWrt
1

Recently I set up dumb AP on my network. I did disable dnsmasq, odhcpd and firewall there. However it appears that during latter OpenWrt update these were re-enabled. This is not really issue for me I disabled these again.

The interesting thing is: when I restarted dnsmasq on the main router the router detected the DNS from the dumb AP and then it started advertising it.

# /etc/init.d/dnsmasq restart
udhcpc: started, v1.36.1
udhcpc: broadcasting discover
udhcpc: broadcasting select for 10.0.0.128, server 10.0.0.100
udhcpc: lease of 10.0.0.128 obtained from 10.0.0.100, lease time 43200
udhcpc: started, v1.36.1
udhcpc: broadcasting discover
udhcpc: no lease, failing
udhcpc: started, v1.36.1
udhcpc: broadcasting discover
udhcpc: no lease, failing

(10.0.0.100 is static IP I assigned to the dumb AP)

Is this normal behavior? Did I possibly misconfigured something?
I do not think this is good. I know that I have to have some trust in devices on demilitarized LAN, but still...

2

OK maybe I am misunderstanding this. Maybe the main router does not advertise it and actually I am getting that DNS probably directly from the dumb AP.

Still what is that log about broadcasting is?

3

When dnsmasq starts up it checks for other DHCP servers on the network. The first lines are showing that it found one. On subsequent starts the other server had been shut down so it got no response to its 'discover' broadcast.

1 Like
4

I guess this was PEBCAK.

5

You can set option force so the discovery is not done which speeds up the startup massively. Handy if you have more then a few networks.