Thanks @HeptaSean I do agree with your general sentiment. Even though I do know what I am doing with name resolutions on my internal network and I run my own caching nameserver internally which is well firewalled from outside. I probably should have modified those example configs to remove the dns names because I am now seeing that this might confuse some users possibly resulting in security issues.
It is probably best to provide example configs using only IPs in the reserved private network range.
Hmmm. I am starting to regret recommending a caching nameserver as a good idea in this other thread as this might require a bit more security and firewalling understanding.