单选题

The most straightforward way tor( )nodes to remain compattbie with lPv4-only nodes is by providing a complete iPv4

implementation. IPv6 nodes that provise a complete IPv4 and iPN6 implementations are called "Pv6/Pv4 nodes"IPv6Pv4

nooes have the abilty to ( )and receive both IPy4 and IPV6 packets. They can direclly interoperate with IPv4 nodes using

IPv4 packets, and also directly interoperate wth IPv nodes using IPv6 packels.

Because they support（ ）,IPv61Pv4 nodes may be conigured wth both IPv4 and IPv6 addresses.IPv6/Pv4 nodes use

IPv4( )(eg. DHCP)to acquire their IPv4 addresses, and IPv6 protocol mechanisms (e g. stateless address auto

coniguration)to acqure their IPv6-native addresses.

The ( )is used in both iPv4 and IPV6 to map between hostnames and P acaresses. Anew resource record type named

"A6" has been defned tor IPv6 addresses wtn support for an earier record named"AAAA".Since IPv6IPv4 nodes must be atle

to interoperate directy with both Pv4 and IPv6 nodes, they must prowce resolver llbrantes capable of deallng wth IPv4"A"

records as well as IPv6"A6"and "AAAA" records.