DNS & DHCP - am I missing something?

I have a server with fixed IP address which hosts my domain's DNS and provides, by DHCP, IP addresses for each of the workstations and laptop computers on my network. DNS happily resolves the server name from all computers. (it's fixed and listed in the DNS configuration files) However, I am unable to resolve, say, a workstation from a laptop other than by finding out their respective IP addresses. Have I overlooked a parameter to allow the dynamically-allocated IPs to be resolved by my name server or is there more to it than that? TIA John