filter-a and dns64 in a ipv6-only network

[Thomas Schäfer]

Am Montag, 30. Januar 2023, 23:12:53 CET schrieb Mark Andrews:
> Do you want a correctly operating DNS64 server or do you want to filter
> all A records?  They are mutually exclusive requirements.  Please read
> RFC 6147 to understand why they are mutually exclusive.

That's simply not true. RFC 6147 is about synthesizing AAAA records based on A 
records. It says nothing about blocking A records afterwards.


> You seem to have this strange notion that to run an IPv6-only node or
> network that you need to filter out A records. 

It isn't  more strange than filtering AAAA records in old IPv4 only networks. 
That filter is ironically implemented by the isc - despite there is no serious 
RFC for that. 
The purpose of the A record filter is to correct the behavior of apps which 
don't respect IPv6 RFCs regarding the preference of IPv6 over IPv4.


> Could you tell me who or
> what told you this was required?

Thank you for the personal attack within the first contact.  I am old (enough) 
-  I can speak for myself. 
I am an experienced user of different IPv6 only networks. 
e.g
daily at eduroam-IPv6only,  a big Wifi network administrated by the Leibniz 
Supercomputinger Centre in Munich, 
daily at the IPv6-only mobile network(4g/5g) by Deutsche Telekom, 
once a year at the RIPE conference WiFi
I am the admin of my home/test lab with: tayga, jool, unbound (filters a, does 
dns64) , dnsmasq (can filter a, but can't do dns64 )

I know that clat is a solution for *some* very old apps, usually on 
smartphones and recently also on macs.
Nevertheless Windows doesn't use clat in wireless/wired LANs.
I want to get rid of clat - aka 464xlat. ( clat was not invented for eternity)
Even linux has no default clat installation on many distributions. 

My experience until now: the a record filter doesn't break anything, but it 
make some apps working  without clat - so at least some windows and linux 
apps.

Now I am testing the usefulness of bind. In the recent state it isn't useful.

Regards 
Thomas Schäfer