Hello,
I was figuring out some questions about use DNS remote requests.
1 - If I use 8 DNS servers, hows MK will decide to use them all?
2 - When one of them goes offline, it will retry to send on some other one?
DNS list would be like:
DNS1 - 8.8.8.8
DNS2 - 8.8.4.4
DNS3 - 1.1.1.1
DNS4 - 1.0.0.1
DNS5…
Anyone knows?
It’s not exactly true, but you can think about it as random. Any of them can be used. If some fails to respond, some other will be queried next. So it’s fine, there’s failover and if at least one configured resolver works, you’ll get the response eventually.
The important thing to understand is what “fails to respond” means. It’s when resolver does not send back any response. Normally it happens when it’s down, you send query and nothing comes back.
But there’s one common misconception that shows up when people use local domains, e.g. popular something.local, something.lan, etc. They don’t exist in global DNS. The unexpected part (for some) is when you ask a resolver not aware of these local domains, it will respond. And the response will be “sorry, that domain does not exist”. And since it’s clear answer, the client (in this case RouterOS) will take it and will not ask another configured resolver for second opinion. So if there’s need to use local domains, you can’t mix local and public resolvers.