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re: NAT-PT: DNS ALG question
I'm not sure if I got what do
you mean. Maybe we can clarify by a typical sequence:
DNS server
(D)
V4
host(A) NAT-PT
v4 host(X)
V6
host(B) DNS-ALG
1. X sends DNS query to D,
which will be intercepted by NAT-PT;
2. NAT-PT modifies
the query to AAAA.
3. NAT-PT relay the query to
D;
4. D replise that that are
no AAAA RR.
If NAT is used, it'll
function after the DNS query returned by DNS server. that's after step
4.
If we explore some other means of communication before
NAT-PT, modification to the applications
will be
needed.
My suggestion is DNS-ALG query
the DNS server before it translates the A to AAAA.
R.G.
Renxiang
At 10:59 AM 11/19/2003 +0800, CTO WEI Renxiang
wrote:
Hi,
I wanted to know
what would be the correct behavior for the following
scenario.
Suppose a mix(include both IPv4 and IPv6 host) network
with a NAT-PT and DNS-ALG deployed
on the
border. An outside IPv4 client host sends a A query, thru NAT-PT, to a DNS
server in this mix network.
NAT-PT RFC says that a A need to be translated into
AAAA,
but if the host in this mix network been
queried is an IPv4-only host, the result will not be correct.
The RFC really doesn't say anything like that.
These two v4 devices should have had some means of
communicating before NAT-PT, which is
probably NAT. And I would assume that
they continue to talk to each other using NAT. If
you say that the NAT and
NAT-PT are running in the same box, then it would become a
coexistence
and/or implementation issue and you won't find those issues in
NAT-PT RFC.
Should DNS-ALG need to query
the DNS server in this mix network before it translates the A to
AAAA?
Thanks
Renxiang