ueries As stated above, a new AAAA resource record type is defined for storing a single IPv6 address. A node making a AAAA DNS query may receive a list of addresses, if the queried fully qualified domain name maps to multiple DNS records. This list of addresses is then utilized by the host's address selection algorithms (see Section 3.5.4). An example of AAAA record is given in Figure 3.24. Reverse DNS Queries For the scenarios where a fully qualified domain name needs to be resolved based on an IPv6 address literal, a domain for IPv6 reverse DNS lookups has been defined. The domain for reverse DNS lookups is hosted at IP6.ARPA. The IPv6 address is represented in the IP6.ARPA domain by listing each nibble separated by dots, starting from least significant nibble, and ending the domain with suffix ip6 arpa, as illustrated in Figure 3.24. Recursive DNS Server Discovery The history related to finding recursive DNS servers' addresses is a very interesting one. Even though the core of IPv6 was defined in the 1990s, it took a long time to agree how nodes ought to discover IPv6 addresses of RDNSSs. This was not initially a very pressing topic, as AAAA and PTR resource records can be queried by talking to DNS servers over IPv4. However, for IPv6-only modes and just for allowing the use of IPv6 for DNS communications, a method was needed to find IPv6 addresses for RDNSSs. Standardization of the DNS server discovery mechanism was a long battle between Router Advertisement and DHCPv6-based approaches. The biggest point of principle was whether IPv6 Router Advertisement should be used for configuring nodes with any other information than what is needed for router discovery and the nodes' stateless and stateful IPv6 address autoconfiguration. In particular, the fear was that if DNS configuration were added to Router Advertisement, soon there would be plethora of proposals for adding Introduction to IPv6 other pieces of configuration information to Router Advertisements (and in fact, there has been and are proposals for adding