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SERVFAIL not handled well #22

raylu opened this Issue · 5 comments

2 participants


python -c 'import dns.resolver; dns.resolver.query("", "TXT")'

This hangs because nameservers aren't removed from the list for SERVFAIL:
The comment is not very helpful in explaining why.


In my understanding, SERVFAIL is

Server failure - The name server was unable to process this query due to a problem with the name server.

I don't see anything in RFC 1035 about temporary failure. Am I (as often happens when dealing with RFCs) reading the wrong document?


Thanks for looking into this. We have lowered our timeouts and that has taken care of our issue for now.

host and dig both seem to respond instantly with an error.

It also seems unreasonable to expect a retry after a SERVFAIL to work in the real world. If there's an issue with the server, that's their problem (other DNS resolvers will fail immediately anyway).


We now do not retry a SERVFAILing nameserver by default

@rthalley rthalley closed this
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