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I'm confused about IPv6 rDNS !

Nibiru
Community Veteran
Posts: 5,797
Thanks: 425
Fixes: 12
Registered: ‎11-08-2007

I'm confused about IPv6 rDNS !

I've been using http://ipv6-test.com/ to check my IPv4+IPv6 connectivity.
One of the things it tells me that I could do to improve my IPv6 connectivity score rating, is -
Quote
Get a reverse DNS record
There is no reverse DNS record to associate your IPv6 address with a host name.
Reverse DNS records are required by some Internet protocols and are usually managed at the ISP level.

I've looked at the available DNS settings for my domain host, and the rDNS setting for a Hurricane Electric IPv6 tunnel,  but I am having trouble visualizing what I am trying to achieve.
For instance -
Looking from the domain hosts point of view, I can set the "A record" to point to an IPv4 and IPv6 address, so presumably that when I browse to my domain, then the DNS will resolve to a specific tunneled IPv6 address on my network where a webserver would be located.
Looking at the Hurricane Electric tunnel account settings, there is a section for "rDNS delegations",  where I can only enter the URL of my domain host's nameservers,  but I can't see how my domain name is associated with the IPv6 subnet.
Looking from my network, where whichever PC I'm using to run the IPv6 connectivity test, could have any IPv6 address allocated (within the /64 subnet) allocated by DHCP or other method (perhaps randomly with privacy extensions enabled),  so I'm struggling to see how an IPv6 address which is likely to be different from the domain "A record" is going to get resolved to a hostname.

Am I over-thinking this in trying to have any IPv6 IP address within a /64 subnet resolve to a domain name ?
Crazy
Plusnet FTTC 80/20 IPv4/30, Hurricane Electric 6in4 IPv6/48, Pulse8 landline & calls, SamKnows 600N
Vigor 130 modem, pfSense 2.6.0 router, DrayTek WAPs, Devolo dLAN 500, Gigaset N300A-IP VoIP DECT
5 REPLIES 5
RPMozley
Pro
Posts: 1,254
Thanks: 53
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Registered: ‎04-11-2011

Re: I'm confused about IPv6 rDNS !

In the HE tunnel settings just set DNS delegation to the HE dns. Then you can use their free DNS record settings to set specific rDNS records for your subnet. Not sure if you can apply that to the whole subnet or not, I haven't look at it for quite some time.
That's RPM to you!!
MJN
Pro
Posts: 1,314
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Registered: ‎26-08-2010

Re: I'm confused about IPv6 rDNS !

Quote from: purleigh
Looking from my network, where whichever PC I'm using to run the IPv6 connectivity test, could have any IPv6 address allocated (within the /64 subnet) allocated by DHCP or other method (perhaps randomly with privacy extensions enabled),  so I'm struggling to see how an IPv6 address which is likely to be different from the domain "A record" is going to get resolved to a hostname.

You wouldn't normally have reverse DNS entries for clients, particularly ones whose address is likely to change as you say. For servers (and other 'fixed' devices) which would normally have a static IPv6 address then a reverse DNS entry is common for logging, verification, etc.
One way to enable reverse DNS entries for clients whose addresses will change is to use a wildcard such that *all* reverse lookups for a given prefix will return the same result. ISPs may opt to do this for logging etc (e.g. 'customer1234.plus.net'). However, this would fail the other usage for reverse DNS records - verification of forward/reverse between names and addresses - because the subsequent forward lookup would likely not resolve back to the original IPv6 address. Alternatively you could add reverse records automatically e.g. with the clients updating the DNS with dynamic DNS or the DHCPv6 server doing so when it hands out an address.
For what's worth, reverse DNS is a common brain acher... and whilst the principles in IPv6 are exactly the same as IPv4, actually putting it into practice is little more difficult!
Nibiru
Community Veteran
Posts: 5,797
Thanks: 425
Fixes: 12
Registered: ‎11-08-2007

Re: I'm confused about IPv6 rDNS !

@'RPMozley' - Thanks, that looks hopeful !  Smiley
https://dns.he.net/
Quote
Free DNS service
Welcome to the Hurricane Electric Free DNS Hosting portal. This tool will allow you to easily manage and maintain your
forward and reverse DNS.
The Open Beta has been expanded and now includes our IPv6 certification or tunnelbroker account holders,

I wonder if that became available after I opened my tunnelbroker account.  Huh
Quote
Features

  • Dualstack: Supports queries via both IPv4 and native IPv6.

  • Support for A, AAAA, CNAME, MX, NS, TXT, SRV, SSHFP, SPF, RP, NAPTR, HINFO, LOC and PTR records.

  • Smart mode IPv4 and IPv6 reverse zones simplifies reverse zones.

  • Slave support

  • Multiple reverse zone formats: Standard, RFC 4183, RFC 2317, DeGroot.

  • Geographically diverse servers.

  • Sanity checking for delegation for both forward and reverse zones.

  • Basic syntax checking for fields.

  • Multiple domains per account.


All the previous reading I had found on this subject referred to creating a shared domain via <afraid.org>
Plusnet FTTC 80/20 IPv4/30, Hurricane Electric 6in4 IPv6/48, Pulse8 landline & calls, SamKnows 600N
Vigor 130 modem, pfSense 2.6.0 router, DrayTek WAPs, Devolo dLAN 500, Gigaset N300A-IP VoIP DECT
Nibiru
Community Veteran
Posts: 5,797
Thanks: 425
Fixes: 12
Registered: ‎11-08-2007

Re: I'm confused about IPv6 rDNS !

Quote from: MJN
For what's worth, reverse DNS is a common brain acher... and whilst the principles in IPv6 are exactly the same as IPv4, actually putting it into practice is little more difficult!

The difference being that IPv4 PCs on a home network are hiding behind NAT, so appear to the outside world as a single public address - which is much easier to point a domain at.
Plusnet FTTC 80/20 IPv4/30, Hurricane Electric 6in4 IPv6/48, Pulse8 landline & calls, SamKnows 600N
Vigor 130 modem, pfSense 2.6.0 router, DrayTek WAPs, Devolo dLAN 500, Gigaset N300A-IP VoIP DECT
TimSmall
Grafter
Posts: 29
Thanks: 13
Registered: ‎15-10-2011

Re: I'm confused about IPv6 rDNS !

It would be really great if Plusnet allowed end-user control of IPv6 reverse DNS e.g. add entries, or delegate reverse to another DNS server - like Andrews and Arnold - AAISP offer with their IPV6 xDSL services.
Perhaps this could be a 'premium' service with a one-off fee (e.g. bundled in with static IP support)?
Any plans for this?