What prefix length must you use when assigning a global NAT-PT prefix? (Select the best answer.)
A. ::/32
B. ::/48
C. ::/64
D. ::/96
E. ::/120
Explanation:
You must use a::/96 prefix length when assigning a global Network Address Translation Protocol Translation (NATPT) prefix. NATPT is used to enable communication between IPv4only hosts and IPv6only hosts by translating IPv4 packets to IPv6 packets and IPv6 packets to IPv4packets.
To enable NATPT, you must assign a global NATPT prefix, enable NATPT on the incoming and outgoing interfaces, and create IPv4toIPv6 and IPv6toIPv4 address mappings. To assign a global NATPT prefix, you should issue the ipv6 nat prefix ipv6prefix/prefixlength command from global configuration mode, where prefixlength is always 96. All other prefix lengths are invalid. To enable NATPT on an interface, you should issue the ipv6 nat command from interface configuration mode on the incoming and outgoing interfaces.
A NATPT router must contain IPv6toIPv4 and IPv4toIPv6 address mappings so that the router knows how to correctly translate IPv4 and IPv6 addresses. There are four methods for using NATPT:
– IPv4mapped NATPT
– Static NATPT
– Dynamic NATPT
-Port Address Translation (PAT)
IPv4mapped NATPT enables IPv6 traffic to be sent to an IPv4 network without requiring that IPv6 destination address mapping be configured. To configure IPv4mapped NATPT, you should issue the ipv6 nat prefix ipv6prefix v4mapped {accesslistname | ipv6prefix} command from global configuration mode or interface configuration mode.
Static NATPT creates static IPv6toIPv4 or IPv4toIPv6 address mappings. To create a static IPv6toIPv4 address mapping, you should issue the ipv6 nat v6v4 source ipv6address ipv4address command. To create a static IPv4toIPv6 mapping, you should issue the ipv6 nat v4v6 source ipv6address ipv4address command.
Dynamic NATPT allocates IPv6toIPv4 or IPv4toIPv6 address mappings from a pool. When a session is established, a onetoone mapping is created; the mapping is then removed when the session is finished. To configure dynamic IPv6toIPv4 address mapping, you should issue the ipv6 nat v6v4 source {list accesslistname | routemapmapname} pool poolname command. You should then create the address pool by issuing the ipv6 nat v6v4 pool poolname startipv4 endipv4 prefixlength prefixlengthcommand. To configure dynamic IPv4toIPv6 address mapping, you should issue the ipv6 nat v4v6 source list {accesslistnumber |accesslistname} pool poolname command. You should then create the address pool by issuing the ipv6 nat v4v6 pool poolname startipv6 endipv6 prefixlength prefixlength command.
PAT allows multiple IPv6 addresses to be mapped to one or more IPv4 addresses.To use PAT with a single IPv4 address, you should issue the ipv6 nat v6v4 source {list accesslistname | routemap mapname} interface interfacename overload command. To use PAT with a pool of IPv4 addresses, you should issue the ipv6 nat v6v4 source {listaccesslistname | routemap mapname} pool poolname overload command. You should then create the address pool by issuing the ipv6 nat v6v4 pool poolname startipv4 endipv4 prefixlength prefixlength command.