[conspire] missing rDNS for (intentionally missing) IPv6

[Michael Paoli]

> From: "Tim Utschig" <tim at tetro.net>
> Subject: Re: [conspire] missing rDNS for (intentionally missing) IPv6
> Date: Wed, 24 Feb 2021 18:41:37 -0800

> On Wed, Feb 24, 2021 at 03:44:38PM -0800, Rick Moen wrote:
>> Comcast Business needs to add this to its rDNS:
>>
>> 9.8.a.b.3.1.e.f.f.f.d.e.0.2.2.0.0.0.1.d.f.2.8.1.4.2.0.3.3.0.6.2.ip6.arpa.  
>> 1h IN PTR linuxmafia.com.

Oh, and TTL, ... perhaps wee bit longer?
I don't suppose you're planning to put and want something else
for "reverse" DNS on that same IP address and Ethernet MAC address
anytime soon, eh?

Let's see ...
$ dig +trace  
9.8.a.b.3.1.e.f.f.f.d.e.0.2.2.0.0.0.1.d.f.2.8.1.4.2.0.3.3.0.6.2.ip6.arpa.  
PTR
...
0.3.3.0.6.2.ip6.arpa.   86400   IN      NS      dns101.comcast.net.
0.3.3.0.6.2.ip6.arpa.   86400   IN      NS      dns104.comcast.net.
0.3.3.0.6.2.ip6.arpa.   86400   IN      NS      dns102.comcast.net.
0.3.3.0.6.2.ip6.arpa.   86400   IN      NS      dns103.comcast.net.
0.3.3.0.6.2.ip6.arpa.   86400   IN      NS      dns105.comcast.net.
...
4.2.0.3.3.0.6.2.ip6.arpa. 3600  IN      SOA     dns101.comcast.net.  
hostmaster.comcast.com. 7 7200 300 604800 3600
...
Well, not sure why they have their SOA TTL down to 3600,
but the NS TTL at 86400.
$ dig +noall +answer +nottl +multiline 4.2.0.3.3.0.6.2.ip6.arpa. SOA
4.2.0.3.3.0.6.2.ip6.arpa. IN SOA dns101.comcast.net. hostmaster.comcast.com. (
                                 7          ; serial
                                 7200       ; refresh (2 hours)
                                 300        ; retry (5 minutes)
                                 604800     ; expire (1 week)
                                 3600       ; minimum (1 hour)
                                 )
$ dig @dns103.comcast.net. +norecurse  
9.8.a.b.3.1.e.f.f.f.d.e.0.2.2.0.0.0.1.d.f.2.8.1.4.2.0.3.3.0.6.2.ip6.arpa. PTR  
| fgrep NX
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 53403
$
Yeah, not yet.

So, ... maybe a TTL of (up to) 86400 ... but not much point in
longer than that.

>> (Ten minutes later:)
>>
>> Talked to Comcast Business Support, and they created an escalated
>> trouble ticket to create the PTR record.
>
> I'm interested to hear how this goes. I'm curious if they've
> improved...

I'm guestimating 24 to 48 hours, based on my prior experience of similar
with IPv4 "reverse" DNS ... but who know.  Might also be some fair
bit of luck-of-the-draw.