Re: Ipv6 DNS and ipv4 host - Tranistion problem
On Thu, Sep 29, 2005 at 10:26:35AM +0800, kmlhk79-ipv6@yahoo.com.hk wrote:
> Dear All:
>
> Since IPv6 is using the root DNS server in Ipv4 to
> search the DNS in the Internet.
>
> It means that the Ipv4 only client Host may get a host
> name resolved but with IPv6 address.
>
> Assume that it is a pure Ipv4 client host, and the
> Ipv6 Host only have IPv6 DNS record in the Ipv4 DNS
> server. ( i.e. No Ipv4 DNS reccord).
>
> The Ipv4 client host should got Host not find on that
> host domain Name .
Yes. To be precise, when the client asks for an A record on an IPv6-only
host, it should receive an authoritative answer that this host does not
have an A record; similar to when a client asks for an A record on a
domain that has NS and MX records, but no A record.
> It will be a problem when transition Ipv4 network to
> Ipv6 network.
No, it will not. If an IPv4-only host requests an AAAA record when
trying to resolve a domain name and errors out when it cannot do
anything with the result, it is broken beyond all repair.
> Becasue we shall not want to keep the Ipv4 address
> mapping record in Ipv4 DNS server when we transition
> to Ipv6 network.
Why not?
Try this:
dig a samba.grep.be
You'll get 195.144.77.39, which is the IPv4 address of my mail (and
other) server. Then try this:
dig aaaa samba.grep.be
This time, you'll get 2001:6f8:32f:0:209:6bff:fe27:7db2, which is the
IPv6 address of the same system. As you see, both address families can
live together without any problem; there is no reason to try doing
strange things.
> However , do not keep DNS Ipv4 address mapping record
> in DNS server will disconnect all the current
> host/server visiting by the Ipv4 only client host form
> internet ( can not resolve DNS).
It will not disconnect anything, for the TCP connections have already
been made. However, if you indeed drop the IPv4 record (and there is no
reason to do so), then IPv4-only hosts will indeed not be able to set up
connections anymore once their DNS cache has expired.
> This problem will post a strong resisit to transition
> form Ipv4 to Ipv6 .
>
> Are there any solution on this ?
There is no problem. If you're interested in the details (and this mail
didn't help), then I suggest you research how the DNS system works; it
is far more flexible than you seem to think. A good resource is the "DNS
and Bind" book from O'Reilly.
--
The amount of time between slipping on the peel and landing on the
pavement is precisely one bananosecond
Reply to: