On 13 Mar 2013, at 01:35, oliver domke <[email protected]> wrote: > You can setup multiple servers, but only one IP is fetched from a DNS > server at a time. That's a fact of the DNS system. If IPv6 is running > properly, AAAA records are priorised. That means that every client able to > use IPv6 will use IPv6.
This is very, very wrong. A DNS lookup with a QTYPE of A returns ALL of the A records the queried server has for the name that was part of the query, not just one A record. Likewise, when the QTYPE is AAAA, the DNS server will return all the AAAA records that it has for the name being queried. There is NOTHING in the DNS protocol for a client to signal that it prefers A records in responses to AAAA records (or vice versa). Therefore DNS clients and servers CANNOT prioritise one type of resource record for an IP address over another in a query or response. It is also downright stupid and wrong for a DNS server to make those assumptions based on the network protocol which delivers a query. It doesn't follow that a host that only cares about IPv6 will only make DNS queries over IPv6. Or one that only wants IPv4 addresses will ise IPv4 for its queries. For example, an IPv6-only edge device may well make a query over IPv6 to its local dual-stack recursive resolver. That resolving DNS server could then look up the AAAA record(s) by making a query over IPv4 to some authoritative server. Similarly, an IPv4-only device will use IPv4 to reach some local dual-stack resolver which then then uses IPv6 to resolve its queries. BTW, it's "IP address" not "IP". _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
