An IPv6-specific resource record, the AAAA resource record, has been specified by in RFC 1886 DNS Extensions to Support IP Version 6. This AAAA record maps a host name into a 128 bit IPv6 address. The PTR record is still used with IPv6 to map IP addresses into host names. The 32 four bit nibbles of the 128 bit address are reversed for an IPv6 address. Each nibble is converted to its corresponding hexadecimal ASCII value. Then, ip6.arpa is appended.