Question about expected recursive resolver behavior

Tony Finch dot at
Thu Apr 23 19:55:03 UTC 2020

Sarah Newman <srn at> wrote:

> What should happen when for a given domain:
> - The domain resolves via TCP but not UDP - UDP for this domain had no
> response at all.

I would expect the domain to be completely unresolvable: the resolver will
only try TCP if it gets a truncated reaponse over UDP.

> - That authoritative nameserver hosts other domains, and those domains
> resolve via UDP.

The lack of response for some domains might cause problems for the other
domains if the resolver decides that the authoritative server is too
broken to bother asking.

f.anthony.n.finch  <dot at>
Bailey: Variable 3 or less, increasing 4 at times. Moderate. Fair. Good,
occasionally poor.

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