I use OpenWRT on my home access - points instead of stock software (due to security concerns and my OpenSourceTheWorld approach).
So I was trying to make OpenWRT send DNS IP address to DHCP clients. By default OpenWRT will send it's own IP (it's using Dnsmasq onboard). And I just couldn't find option to set this manually (using webinteface).
Finally I logged into CLI interface via SSH and found that this change can be made in two ways.
In /etc/dnsmasq.conf by adding line:
Or in /etc/config/dhcp by adding to the section config dnsmasq:
list 'dhcp_option' '6,192.168.1.29'
Just restart Dnsmaq service afterwards and you're done.