S: 0 Queries Answers III www.ietf.org: type AAAA, class IN, addr 2001:1890:126c::1:1e Name: www.ietf.org Type: AAAA (IPv6 address) class: IN (0x0001) Time to live: 14 seconds Data length: 16 Addr: 2001:1890:126c::1:1e Figure 3.33 Example: DNS response with AAAA record. sent over the IPv4 independently of the address family being resolved - the query type has no relation to the address family used to transport the query. In this case the DNS queries are sent to an address of 192.168.1.1 1 that happens to be a local DNS proxy, as the nodes on the used dual-stack access network are not provisioned with any IPv6 address for DNS servers. The first trace entry we have opened, trace log entry number 8, is the one showing the DNS query for an AAAA resource record. The queries for an A resource record are as performed in the usual IPv4 manner and hence we skipped those. In the highlighted entry, the implications of IPv6 to the DNS protocol are visible in the 'Queries' section, which is showing a type AAAA resource record being requested for the www.ietf.org. course one major implication of IPv6 to systems is the need to send a second DNS query in the first place. A DNS response containing an IPv6 address in an AAAA type of resource record is only slightly different from that of IPv4. In Figure 3.33, at trace log entry number 9, the successful DNS reply containing an AAAA record is highlighted. The AAAA resource record is otherwise exactly as the A resource records, but it contains a identification of type AAAA and full IPv6 address for the www.ietf.org, which at the time and place of this packet capture was 2001 : 1890 126c: : 1: : le. The DNS response could have also contained some other information such as additional AAAA or canonical domain name records, but in this case the response contained only a single resource record. After the host has successfully and quickly received both IPv4 and IPv6 addresses for the destination it is connecting to, the host performs address selection algorithms and, as usually happens for 