Multiple DNS, priority of Servers [closed]

Solution 1:

If the Primary server can be reached, it will only query that server. If the query doesn't return anything it will send it to its forwarders, but if they don't return anything it will fail at that point. It won't continue on to the secondary DNS server.

It uses the secondary DNS server if the primary is not responding to DNS queries at all.

The secondary DNS server is NOT there as a fallback query (think forwarder) in case the primary DNS server doesn't know the answer.

Also, Evan and Joe: How does Windows decides which DNS Server to use when resolving names?

Also:

https://serverfault.com/questions/130608/when-is-a-secondary-nameserver-hit

Why should one have a secondary DNS server?