The integrated DNS function resolves names to IP addresses and vice versa based on the same data repository as the DHCP server itself. All information is stored in the INI file. All clients that have been added to the INI file, automatically or manually, can be resolved. Assuming the following INI file:

[General]
DOMAINNAME=mydomain.local

[00-01-02-03-04-05]
IPADDR=10.5.60.7
Hostname=pc1

With this INI file, the DNS function will resolve the IP address 10.5.60.7 to pc1.mydomain.local and vice versa.
Say you want to add a DNS record for a client that is not represented in the INI file. A reason why this might be necessary is because you have clients with static IP address on the network not DHCP assigned. Simply add the following lines to the INI file:

[IP_10.5.60.8]
IPADDR=10.5.60.8
Hostname=pc2

Now the DNS function is able to resolve pc2.mydomain.local. It’s IP address is 10.5.60.8. Please note that the section name for pc2 is choosen as IP_… The client section name has no particular function besides being a unique one for each client. Usually this is the MAC address, because this is the identifier used by DHCP. But if the client is only added to the INI file for the purpose of DNS resolution than it is ok to not use the MAC address.