DNS64 & nslookup

Mark Boolootian booloo at ucsc.edu
Wed Apr 11 23:26:34 UTC 2018


>> As far as I know, a host with on an IPv6 address is only ever
>> going to perform AAAA lookups.  I'd be very interested to know
>> if there are cases where that isn't true.
>
> Well, if you run nslookup or dig -t a, you're asking for A records
> explicitly.

Ah, true that.  Does nslookup do that by default?

> OK, fair enough.  If you ask a DNS64 server for an A record, it should still
> give you back an A record.  If you ask for an AAAA RR, then you will get back an
> AAAA record, even if it has to synthesize an A record into a 6-in-4 IPv6 address.

Yes.  And this was what seemed weird about the original
question.  In my experience, an IPv6 only host (and IPv6
only means no routable v4 address - so you might have
169.254, but nothing else) only emits AAAA lookups.  But
maybe I need to look more carefully.  I'm working towards
building an IPv6 only environment here, and my (often
erroneous) thinking presupposes certain behavior.

cheers,
mark


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