Hi,
In my opinion too, mapped addresses should never be present in
db files. The resolver calls like
getipnodebyname()/getaddrinfo() or other calls will dynamically
generate IPv4-mapped-IPv6 addresses.
This has been made amply clear in RFC2553 although implicitly.
It says that getipnodebyname() calls should generate
IPv4-mapped-IPv6 addresses on fly when it cannot find AAAA
records. The call will query for A records and generate mapped
addresses from these records and return the results. This
inturn implies that no mapped addresses should be present in db
files.
But what seems to be ambiguous is IPv4-compatible-IPv6
addresses. There is no reference about this except in
getipnodebyaddr() in RFC2553 which says that initial 12 bits
needs to be stripped and then query is made for the IPv4 address
in in-addr.arpa domain.
This seems to suggest that we need to have a PTR record for
IPv4-compatible-IPv6 addresses in in-addr.arpa domain as is the
case with A records (IPv4 addresses) and not IP6.INT domain.
But how about forward resolution, should AAAA records or A
records need to be generated for IPv4-compatible-IPv6 addresses.
There is a reference in "Unix Network Programming Volume-1 by
Stevens" that says IPv4-compatible-IPv6 addresses should have
AAAA records which was probably written before RFC2553 was
drafted. But there seems to be little inconsistency b/w this
reference in UNP-1 by Stevens and RFC2553 which states for
reverse resolution it has to take it from in-addr.arpa domain.
Or does it mean that forward resolution uses AAAA records for
compatible addresses and in-addr.arpa domain (IPv4 address
reverse domain) for address -> nodename resolution.
Actually there is no flag similar to AI_V4MAPPED for generating
IPv4-compatbile-IPv6 address?? Is this a required one?
Any ideas regarding IPv4-compatbile-IPv6 addresses.
Cheers,
Praveen
>
> On Wed, May 09, 2001 at 01:04:31PM +0200, Sogor Laszlo wrote:
> > In the root.hint file of IPv6 DNS server there is an IPv4-mapped address
> > (::ffff:0:0/96):
> >
> > . 3600000 IN NS ns.root
> > ns.root 3600000 AAAA ::ffff:192.168.1.2
>
> In my opinion mapped addresses should never ever be used in the DNS
> or on the wire. Only exception for using it on the wire is SIIT,
> with NAT-PT you should choose some other prefix if possible. You
> might have a look at RFC 2766, and look for where it says PREFIX.
>
> > So BIND don't handle IPv4-mapped IPv6 addresses, but mapped addresses must
> > be used because of the NAT-PT. :((
>
> No, or are mapped addresses hard coded in the implementation?
>
> Stig
>
>
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HP India Software Operations Telnet : 847-1306
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