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Announcing IPv6 DNS resolver
![[nl]](/s/countries/nl.gif) Shadow Hawkins on Friday, 03 December 2010 09:19:57
I have a SixXS subnet set up at home. I have registered some AAAA DNS records for some of my hosts, and also set up ip6.arpa reverse records. I've set up a rtadvd daemon to broadcast IPv6 addresses and the default route.
But now I'm wondering, how do I announce an IPv6 DNS resolver over IPv6?
I've been searching everywhere, here on the site, FreeBSD handbook, google, but all to no avail. It's almost as if the problem doesn't exist?
Announcing IPv6 DNS resolver
On Linux one has radvd which supports RFC5006, afaik the *BSD version (rtadvd) does not support this option, as also confirmed by this message: RDNSS (RFC5006) support with rtadvd/rtsold.
Guess you'll have to upgrade to Linux (kidding ;) or better, get *BSD to implement the option.
Anyway.... there is an easier method at the moment which is, I guess, what most people use: IPv4 DHCP for IPv4-address + DNS servers, IPv6 RA for getting an IPv6 address.
Announcing IPv6 DNS resolver
Shadow Hawkins on Friday, 03 December 2010 10:11:52
Could IPv4 DHCP annnounce a IPv6 nameserver?
I'm not on a IPv6 only network, but just wondering in case I ever do want to switch over to a v6 only network.
It just seems strange that my whole network is set up dual stack, mail, DNS, rtadv, etc. and IPv6 clients can connect automatically, but then can't do anything.
Announcing IPv6 DNS resolver
DNS is DNS, what transport it runs over does not matter.
Note the differences in terminology here:
* IPv4|IPv6 Transport = the protocol the requests are made over.
* IPv4|IPv6 Resolving = asking for A or AAAA and other records.
While IPv4 DHCP can't provide IPv6 Transported DNS servers, doing IPv6 Resolving over IPv4 Transport works perfectly fine.
If you really want to see IPv6 Transported DNS servers then upgrade your rtadvd or go for DHCPv6.
Note though that a number of applications can't handle having an IPv6 address in /etc/resolv.conf and for the rest there is not really an advantage doing resolving over IPv6.
Announcing IPv6 DNS resolver
![[dk]](/s/countries/dk.gif) Shadow Hawkins on Friday, 03 December 2010 09:42:03
Just my opinion, no solution:
I think most networks also provide ipv4-adresses and ipv4-nameservers over ipv4-dhcp. Even if it is 192.168 - type local adresses.
I think few have ipv6-only networks, so your problem is somewhat unique.
Announcing IPv6 DNS resolver
Shadow Hawkins on Friday, 03 December 2010 09:43:28
I swear your reply wasn't there when I started :-)
Announcing IPv6 DNS resolver
![[ch]](/s/countries/ch.gif) Shadow Hawkins on Friday, 03 December 2010 11:49:52
I'm interested in the same question, but from an IPv6-only networking point of view. From what I could tell so far, most operating systems don't yet support by default anything beyond address and route configuration. Windows might try to use special "well-known" addresses (according to Wikipedia they are deprecated). There might be some Linux distributions that install a DHCPv6 client by default. As far as I can tell, most systems won't work out-of-the-box on an IPv5-only network.
There seem to be three possible mechanisms for finding DNS servers:
- RDNSS (mentioned by Jeroen above): announcing this is implemented in the radvd deamon on Linux, but I think you need to install an additional program on the client.
- DHCPv6: Can be done stateless (no address configuration, only configure additional information like DNS servers)
- Windows seems to use special "well-known" addresses on the local network, like fec0:0:0:ffff::1 (see http://tools.ietf.org/html/draft-arkko-ipv6-only-experience-02#page-6)
I also wonder whether a DNS server (or proxy) should be found over the special multicast addresses for DNS servers, like ff02::fb (All DNS servers on the local link), as is mentioned in the free IPv6 book (http://www.sixxs.net/news/2010/#freeipv6booklawrenceehughesthesecondinternet-201006).
Which approach should be favored?
Announcing IPv6 DNS resolver
The fun thing is that for instance Windows XP can't even use IPv6 as a DNS transport, still it has that site-local address in its "production" stack. It is just ignored and it does not work.
Like everything RDNSS requires support on both client+server, in that case for Linux even kernel and userland support.
And no, don't use any of the special 'multicast' addresses for DNS, DNS does not nicely work over multicast unless you are talking about MDNS which is quite a different protocol (and quite noisy on the link too).
The approach that is favored is the one you like, you have the options, choose.
I tend to use DHCPv4 + RA, which works like a charm and I don't have to install anything anywhere as more or less everything understands that per default.
Announcing IPv6 DNS resolver
![[us]](/s/countries/us.gif) Shadow Hawkins on Friday, 03 December 2010 14:58:27
Every approach I have seen to solve this problem has involved DHCPv6 and RA. From what I understand, the "official solution" is to do RA for addresses and DHCPv6 for things like DNS servers.
Announcing IPv6 DNS resolver
DHCPv6 requires RA. With RA you tell that the router is there (RA stands for router advertisement) and in that RA you tell the client to use a specific prefix and to ask for the EUI-64 portion and other optional params using a managemd protocol, eg DHCPv6.
There is no 'official' solution (who would make it 'official'?), you have a lot of options though.
amongst others:
- RA with RDDNS option
- IPv4 and IPv6 DHCP for IP address + gateway + DNS servers etc
Or a combination of those.
Announcing IPv6 DNS resolver
Shadow Hawkins on Monday, 06 December 2010 14:36:19
I'd love to do RA with RDDNS. However, I know that using a Cisco device as your router doesn't allow you to do this.
Will Windows or any other major OS accept a DNS server via RA?
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on Friday, 03 December 2010 09:40:30
Posting is only allowed when you are