Calculate your IPv4 into a NAT64 synthesized IPv6 address:



Calculate IPv4 from synthesized NAT64 address:



Sample configurations for NAT64 & DNS64:

interface GigabitEthernet8
 description To Internet
 ip address <ipv4 address & mask>
 no ip redirects
 no ip proxy-arp
 duplex auto
 speed auto
 nat64 enable
 ipv6 address FE80::2 link-local
 ipv6 address <your ipv6 address>/64
 ipv6 enable
 ipv6 nd ra suppress all
!
interface Vlan666
 description IPv6 Only
 no ip address
 nat64 enable
 ipv6 address FE80::1 link-local
 ipv6 address <your ipv6 address>/64
 ipv6 enable
 ipv6 nd autoconfig default-route
!
ipv6 access-list NAT64
 permit ipv6 <your ipv6 only subnet>::/64 64:FF9B::/96
!
nat64 v4 pool NAT64-IPv4 <v4 start & end addr.>
nat64 v6v4 list NAT64 pool NAT64-IPv4 overload
!
options {
	// other config snipped
	dns64 64:ff9b::/96 {
		clients {
			<your ipv6 only subnet>/64;
		};
	};
};

Note: replace everything that is in between of "<" & ">".