You will need to delegate individual /48s. Assuming your /32 is 2001:DB8::/32
your zone is 8.b.d.0.1.0.0.2.ip6.arpa
. Reverse zones are done by dotted nibbles. That is why recommended sub-delegations are a /56
or a /48
. This yields 256, and 65356 /64 subnets respectively.
If you assign 6 zones starting with 2001:DB8:1234/48
, you would need to delegate the relative addresses 4.3.2.1
through 9.3.2.1
It appears your clients are requesting the capability to create 393216 subnets. Each network segment requires a /64 subnet. Each device will have one or more /128 addresses. Normally a device on the network segment (usually the router) will announce the applicable /64 subnet. In place of DHCP, devices can self-configure based on the announced subnet. It is still possible to assign fixed IPv6 addresses for devices such as servers, routers, and printers. Each /64 subnet has about 2^64 (18,446,744,073,709,551,616) addresses available for devices.