Non domain dhcp clients do not get a DNS record when they receive a lease.
Add new user with a password that does not expire. Add member to the DHCP Administrators security group.
Open DHCP console, connect to DHCP server and access IPv4 properties. Under the Advanced tab, specify the credentials you specified earlier.
I found restarting the DHCP and DNS services had no effect, so in my experience rebooting the Windows Server 2012 R2 box that hosted DNS and DHCP did the trick.
Now I see various wireless clients, including non-domain joined windows laptop and iPhones with names that now resolve to IP addresses.
It is worth a mention: I disabled secure updates.
Apparently you can acheive the same thing by adding the DHCP server to the DNSUpdateProxy group. But, this is a security risk if the box that DHCP is running on is also a domain controller. That is because the AD records can be written to by anyone. OpenACLOnProxyUpdate setting can mitigate the risk. The recommended solution is to specify credentials for the dynamic DNS update.