Subject: (ngtrans) draft-hallin-natpt-dns-alg-solutions-00.txt

From: Grigory Kljuchnikov <[email-masked]>
Date: Fri, 28 Jun 2002 16:59:48 +0400 (MSK)

Hello,

Some commets:

1)
   2.1 AAAA answers for A queries

   ...

   ---------------------------------------------------------------------
   => NAT-PT should only be used by IPv6-only nodes.  These nodes should
   not use IPv4 DNS (A), thus the NAT-PT should refuse any A queries
   made by internal nodes.
   ---------------------------------------------------------------------

=> Another solution is to keep a track of DNS queries (each DNS query/answer
has an unique ID). When it was an A query from an internal node, DNS-ALG
returns A answer to the requester (without changing to AAAA).
I think IPv6-only nodes can send A queries and DNS-ALG can provide this
ability.

2)
   2.3 NAT-PT & IPv6 default router
   ...

   However, a more scalable approach is that IPv6-only clients connected
   to the NAT-PT, do all IPv6 DNS resolution over translated IPv4.  The
   IPv6-only clients set NAT-PT_PREFIX:ipv4_dns as their DNS server,
   where NAT-PT_PREFIX is the NAT-PT prefix in the NAT-PT domain and
   ipv4_dns is a DNS server in the IPv4 domain.  All DNS messages will
   then be routed through the NAT-PT.  Dual-stack nodes will continue to
   use their ordinary DNS server.  Their DNS traffic will not be routed
   through the NAT-PT.  Thus, dual-stack nodes have no contact with the
   NAT-PT in the network.  The NAT-PT is not required to be the default
   IPv6 router of the site.  Only traffic in need of translation will be
   routed through the NAT-PT.  This set up works provided that the IPv4
   DNS server supports IPv6 DNS.

   ---------------------------------------------------------------------
   => It is not necessary for the NAT-PT to be the only default router
   in the IPv6 domain.  The only traffic that has to go through the NAT-
   PT is the one that needs to be translated.
   ---------------------------------------------------------------------

=> In this case IPv6-only nodes cannot resolve names of IPv6 hosts (AAAA), because
RFC NAT-PT doesn't say what DNS-ALG has to do with AAAA queries from IPv4 side.
I don't understand what does it mean "the IPv4 DNS server supports IPv6 DNS"?
Does it mean that the IPv4 DNS server can resolve names of IPv6 hosts?
Or it can interact with IPv6 DNS servers? Or it has IPv6 names?

For example,
If internal IPv6-only nodes resolve all names via the external IPv4 DNS server
and we have "ordinary DNS server" inside NAT-PT (where internal names reside),
all quereis (AAAA) for internal hostnames from IPv6-only nodes will go
to the IPv4 DNS server through the DNS-ALG, then to the ordinary DNS server
through the DNS-ALG (where these names reside), then to the IPv4 DNS server
through the DNS-ALG, then to the requester through the DNS-ALG. What
should DNS-ALG do with such intermediate AAAA query/answer from IPv4 DNS
server to internal IPv6 DNS server?

Best regards,

Grigory Klyuchnikov, System Engineer,
Institute for System Programming
Russian Academy of Sciences