I believe this - from the linked tutorial - is incorrect:
"Note B: Your DNS queries will hit the AWS DNS server in the first line first, if it returns nothing, it’ll fall back to the standard Google DNS servers. This allows you to query your local DNS names as well as anything on the internet."
We found the following -
https://serverfault.com/questions/466369/bind9-do-forwarders-have-any-priority - which states:
"BIND8 and onward consider each of the forwarders begin with "equal weight". Based on the SRTT of the responses, the nameserver begins to favor one over the other. A certain percentage of queries will always hit the one with higher latency, to retest the waters and keep the calculated weight preference fair. (bearing in mind that once a record is cached, the forwarders will not be consulted for it again until the TTL has expired)
In short, the forwarders directive is designed with redundancy and minimized latency in mind -- not in an active-standby failover model. This will not do what you want it to, and I am not aware of any BIND directives to reconfigure this behavior. I end up staring at BIND documentation a fair bit in my line of work so I feel pretty confident about this statement."
