Re: Implementing DNS client for support IPv6/IPv4

"sasson, shuki" <sasson_shuki@emc.com> writes:

> 1.	What QTYPE should I use in order to get all the IPv4 and IPv6
> addresses A, AAAA, A6? Is that possible through one query or multiple
> queries are needed?

I'n not really a DNS expert, but I've been hacking the adns resolver
to add IPv6 support, and my conclusions are as follows:

  1. Make two separate requests for A and AAAA. Preferably, send both
     in parallel. In theory, you could make a single request with
     QDCOUNT=2, but then bind (and probably other name server software
     as well) will refuse to answer your requests.

  2. Don't bother with A6. A6 is controversial, and not needed for
     IPv6 support in the forseeable future. I doubt (and hope) that A6
     will never be deployed.

If you only want IPv4 addresses, you naturally send only one request,
for A records. If you only want IPv6 addresses, you may want to send
requests for both A and AAAA addresses anyway, and convert any
received A records into "IPv4-mapped IPv6"-addresses to be returned to
the application.

Regards,
/Niels

--------------------------------------------------------------------
IETF IPv6 working group mailing list
ipv6@ietf.org
Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------