[dns-operations] IPv6 & IPv4 addresses

George Barwood george.barwood at blueyonder.co.uk
Thu Mar 17 15:41:47 UTC 2011

----- Original Message ----- 
From: "Simon Munton" <Simon.Munton at communitydns.net>
To: <dns-operations at mail.dns-oarc.net>
Sent: Thursday, March 17, 2011 2:13 PM
Subject: [dns-operations] IPv6 & IPv4 addresses

>I see from another thread some resolvers are using ANY to do a single 
> query to get both A & AAAA addresses. This may be fine generally, but 
> could cause a lot of traffic for :-
> exmaple.com in ns example.com
> which seems to be increasingly popular.
> So my question is - is there a case for always returning *both* A and 
> AAAA records in response to an A (or AAAA) query - can anybody see any 
> harm in doing this? (other than a slight increase in response packet size).
> Or is there a case for creating a new, virtual RR, called (say) ADDR so 
> a query for ADDR would mean "give me both A & AAAA" ?

I don't think that's necessary. It would be good (and more realistic) for servers to return
both A and AAAA records in response to an A or AAAA query, and also
the NSEC/NSEC3 record that proves the non-existence of the type not queried for where
it doesn't exist ( this could be routine ). The extra records could go in the Additional section.

And then for resolvers to use this information to avoid unnecesary queries.

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