IPv6 reverse DNS in 60″

Your allocation: 2001:db8/32
You LAN: 2001:db8:2:2001/64
Your device: 2001:db8:2:2001::11 (mydevice.local)

Let «host» do the dirty work for you!

sotiris@jumbo:~$ host 2001:db8:2:2001::11
Host 1.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.2.2.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa not found: 3(NXDOMAIN)

The zone for your /32 is 8.b.d.0.1.0.0.2.ip6.arpa

$TTL 1d
@    IN    SOA ( 42 1h 15m 30d 10m )
     IN    NS    localhost.
;
1.0.0.2.2.0.0.0    IN    NS    localhost. ; delegate 2001:db8:2:2001/64

The zone for your /64 is 1.0.0.2.2.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa

$TTL 1d
@    IN    SOA ( 42 1h 15m 30d 10m )
     IN    NS    localhost.
;
1.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0 IN PTR mydevice.local.

Reconfig and run host again

sotiris@jumbo:~$ host 2001:db8:2:2001::11
1.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.2.2.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa domain name pointer mydevice.local.