[RFCI-Discuss] IPv6 and BogusMX

[Derek J. Balling]

On Mar 23, 2008, at 3:04 PM, Jimmy Hess wrote:
>>    - A couple syntactically valid IPv6 addresses ... things which I
>> could use to
>>        - prove that doing a straight MX_hostname -> valid_ipv6 test
>> "passes"
>>        - prove that doing MX points to IPv6 address fails
> Well, MX RRs don't point to ip addresses, they contain a record
> "owner" name in the DNS, i.e. of A, AAAA, or other record.
> AAAA records contain IPV6 addresses   (128 bits in network-byte  
> order).

Yeah, I know that, hence "fails" :-)

> I haven't seen a strict equivalent to IPv4's RFC1918 for IPv6  
> addresses
> that state  the "local only"
> addresses _must_ be kept out of the DNS, though it's still a good  
> idea,
> the RFCs may just not require it.

well, an MX record that's in "1918" equivalent in IPv6 isn't  
reachable, so it would be bogus, no?

> Some domains may use intentionally unavailable MXes as part of an
> anti-spam scheme, but
> the IPs  used should have proper RDNS, and at least one mail server
> operational at all times.

Unavailable is one thing, but using "1918" space is not "unavailable"  
as "your" 1918 space and "mine" might collide. :-)

cheers,
D

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