Score:-1

Can a DNS server accept queries from both IPv4 and IPv6 clients?

cn flag
M9A

I have a remote BIND9 server with an IPv4 address that clients use for their DNS queries. This is mainly a forwarding server where most queries get forwarded to Google’s DNS servers. This works perfectly fine when the client making the request is on an IPv4 network. However, if the client is on an IPv6 network then my BIND9 server ignores the queries.

Is there anything I can do on the BIND9 server so it can answer queries from IPv6 clients as well as IPv4 clients? I have been looking into DNS64 but I am not sure if that is the answer to my issue.

FYI, the client machines have all been configured to use the BIND9 IPv4 address in their DNS settings. For the sake of keeping things simple, I would prefer them to continue contacting the same IPv4 address.

Score:2
cn flag

You have to configure your server accordingly, but this is really a basic feature existing since a long time.

https://ftp.isc.org/isc/bind9/cur/9.19/doc/arm/html/reference.html#namedconf-statement-listen-on-v6

listen-on-v6

Grammar: listen-on-v6 [ port ] [ dscp ] [ tls ] [ http ] { <address_match_element>; ... }; // may occur multiple times

[..]

Specifies the IPv6 addresses on which a server listens for DNS queries.

Other than that you are not giving any details on your problems, not even the bind version, or some dig runs, so it is hard to pinpoint something more relevant for your case.

M9A avatar
cn flag
M9A
This will make the server listen on it’s IPv6 address no? I am asking how it can continue listening on its IPv4 address but serve both IPv4 and IPv6 clients
Patrick Mevzek avatar
cn flag
"This will make the server listen on it’s IPv6 address no? " **IN addition** of its IPv4 addresses. Which is why you have `listen-on` vs `listen-on-v6` configuration parameters.
M9A avatar
cn flag
M9A
I understand but maybe I didn’t explain myself properly. All of the client devices are configured to use the IPv4 address of my BIND server. So if I was to do listen-on-v6, how would that make an IPv6 client make a query through the configured IPv4 DNS address? This is why I suggested possibly DNS64
Patrick Mevzek avatar
cn flag
"All of the client devices are configured to use the IPv4 address of my BIND server. " So then why do you want IPv6? It should of course be the opposite, as IPv4 is legacy, so internally your network should be full and only IPv6. "So if I was to do listen-on-v6, how would that make an IPv6 client make a query through the configured IPv4 DNS address? " I don't understand what you mean here. If nameserver has an IPv6 and listen on it, an IPv6 enabled client will use it, and IPv4 has nothing to do there anymore. DNS64 is related to IPv6 **content** in the zone, not IPv6 connectivity.
M9A avatar
cn flag
M9A
“So then why do you want IPv6?” Some clients are on IPv6 networks and need to connect to the DNS server for which they only have the server’s IPv4 address. In simple terms, if I am a IPv6 client, can I send a DNS query to a DNS server using it’s IPv4 address?
Patrick Mevzek avatar
cn flag
Your are making things complicated for no reasons. For IPv6 clients configure the IPv6 DNS server IP address and job is finished.
M9A avatar
cn flag
M9A
I get that, but hypothetically could a IPv6 client use the IPv4 DNS IP and get a response? I’m talking about a scenario where a client is IPv4 and is configured to query the IPv4 DNS server but at some point in future the client is now on a IPv6 only network. As the client was already configured to query the IPv4 DNS server, could I simply make changes on my DNS server to allow queries from the client?
Patrick Mevzek avatar
cn flag
" could a IPv6 client use the IPv4 DNS IP and get a response?" No, and no matter which protocol. IPv4 works with IPv4 and IPv6 works with IPv6. 2 separate worlds. If you need to go from one to another you need specific gateways/NATs.
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