Ipv6 transformed into readable hostname only after restart of DNS resolver

I am running raspi with pihole and unbound, fritz.box with 7.50 OS, set pihole with ipv4 and ipv6 fd00 address as dns server in FB, also within network-network settings ipv4 and ipv6 as local DNS.
ULA is always set, DHCPv6 is DISABLED (means auto config SLAAC for devices is set).
In pihole DNS I have ticked and set in advanced DNS settings ALL options EXCEPT "Never forward reverse lookups for private IP ranges" means this option is NOT set.

I do have devices showing up regularly with their hostname and some devices showing up with their ipv6 (fd00) address (different one every time devices connects) - mainly amazon tablets and PC.

After restart of DNS resolver in pihole the fd00 address is transformed into the "nice" hostname.

Q: Is there a way the dns resolver in pihole is doing that automatically? are my settings somehow wrong?

any advice here? Still really frustrating that IPV6 address mapping to hostname not properly working - maybe due to config problem on my side?

Please upload a debug log and post just the token URL that is generated after the log is uploaded by running the following command from the Pi-hole host terminal:

pihole -d

or do it through the Web interface:

Tools > Generate Debug Log

@yubiuser , thanks,
Your debug token is: https://tricorder.pi-hole.net/S10M283q/

With IPv4, a DHCP client will indicate its hostname when registering for a lease, allowing a DHCP server to inject that name into a co-hosted DNS server (not all routers will actually do this - your FritzBox does).

There is no equivalent mechanism for IPv6.

This turns reverse lookups for local IPv6 addresses into a guessing game of sorts.
pihole-FTL/dnsmasq would apply some heuristics to associate a given dual-stack machine's IPv6 adress with the hostname for an IPv4 of the same host.
It may be possible that your FB does something similar, but in either case, that's not guaranteed to always work.

On top of that, IPv6 addresses are designed to change regularly, and public GUA IPv6 addresses are resolved by your ISP's public DNS servers, so the hostname will be administrated by them (you'll often see a generic name for those that can be mistaken for an IPv6 on first glance, e.g. somehing similar to 2a02-abcd-dead-f00d-1234-5678-abcd-ef00.pool.telco.com).

To avoid this, I'd recommend to NOT advertise or offer an IPv6 DNS resolver address in your home network (again, not all routers would support this - your FB does). That way, clients will talk to your Pi-hole strictly via IPv4, making it a lot easier to associate them with hostnames (see e.g. Unresolved ipv6 adress in my top list - #4 by Bucking_Horn).
As DNS is indifferent to the transport protocol used, your Pi-hole will continue to supply AAAA as well as A replies to your clients as requested, allowing them -as ever- to use IPv6 addresses from those AAAA records or IPv4s from A to establish communications as they prefer.

2 Likes

@Bucking_Horn
Thx for the information, where is the correct place to switch that off in the FB?
Is it

or

or

grafik

I guess it should be that point?

DNSv6-Server auch über Router Advertisement bekanntgeben (RFC 5006)

See my linked topic above. :wink:

my bad, sry :slight_smile: I'll test and checkout, thanks for the advice

@Bucking_Horn seems to work :slight_smile: thanks a ton!!! that ipv6 was giving me a bad time