CoovaRadius+Open-Mesh+OpenDNS

I'm starting this topic after reading the following post in a Meraki forum: http://tinyurl.com/58vmrm
My research led me to nslookup and the following page which raised more questions than answers (as usual): http://homepages.tesco.net/~J.deBoynePollard/FGA/nslookup-flaws.html
I'm trying to figure out how DNS server settings are determined since they can be set in many different places in a network, e.g. the PC (usually left in automatic by default but can be set manually), WLAN router, DSL modem etc.
Which setting takes precedence?

Re: CoovaRadius+Open-Mesh+OpenDNS