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Sanya Snex
Asked: 2015-09-25 23:38:33 +0800 CST

Whether all attempts to determine the ip address successfully if Master DNS shutdown and secondary DNS work [duplicate]

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Domain exemple-domain.com has two DNS server: dns1.exemple.com (master) and dns2.exemple.com (slave).

questions: If dns1.exemple.com temporarily disabled and dns2.exemple.com works, is it possible that some attempts to define ip addresses fails?

I try it many times in succession

dig @8.8.8.8 exemple-domain.com | awk '/^;; ANSWER SECTION:$/ { getline ; print $5 }'

and part of the query does not receive a reply

Could there be a part of that traffic would be lost if dns1.exemple.com not working and dns2.exemple.com work?

domain-name-system

1 Answers

  1. That depends.

    If the first server simply isn't answering at all, resolvers should retry their queries against the other one. It is, of course, up to them if they actually do retry or not. And it's another question if the second name server will be able to answer. If it is a slave server and the master server has been gone for too long, all the data the slave had will have expired, so it cannot answer questions (it will still send a response, saying SERVFAIL, though).

    So, yes, it could be as you think. As in, it's not impossible. But it is impossible for us to do more than guess wildly until you tell us which domain you're talking about.

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