Is DNS of open sense parallel?

[Jyling]

Does open sense query the configured DNS servers in parallel and return the 1st retrieved answer?

[pfry]

It appears to me the built-in client queries the servers one at a time, in order. That is, I just get one request, to the primary. (I didn't try setting a fake one to test failover.) The behavior may be configurable... but I prefer the default.

[Jyling]

How do you know that you get one request?

When I enter dns1, dns2, and dns3 where their response times are 100ms, 50ms, and 25ms, I get results in 25ms. This is only possible if the request is parallel or some logic tests them and prefers the fastest.

[pfry]

How do you know that you get one request? [...]

Firewall logs (I have logging enabled on all filters). In this case, the "let out anything from firewall host itself" rule.

[Jyling]

It is absolutely inexplicable how the resolution occurs quicker than the response time of the 1st, slow server. This does not make any sense.

[Greg_E]

Is it possible that whichever DNS service you are using goes out and queries the upstream providers, finds the fastest, and uses that one first for all future requests?

I do not see mine querying multiple servers either, but it does sometimes show switching between the two upstream servers.

[Jyling]

Not using the same name for testing.
Were the results cached, the response time would have been lower than the quickest, 3d server, but it is always equal to it.