DHCP Server allots the IP addresses to computers, while DNS server resolves them. You need DHCP Server if you do not want to manually maintain IP Addresses or you have less IP Addresses than number of machines you have, as dynamic DHCP Server will recycle IP Addresses on machines.

DNS Server is needed for resolving hostnames to their IP addresses. Normally your ISP will provide you with DNS Service. You may have your own DNS Server, which will resolve hostnames by forwarding them to ISP's DNS Server and cache the addresses also.

If you have home/small office network with Unix/Linux machines, these machines will not be resolved from each other, as Unix/Linux machines do not support NBNS protocol and you need your own DNS Server. But how about resolving your local machines ?. Your ISP's DNS Server will not have this list and your own DNS Server wont have them either. Most DNS Servers cannot do this.(unless you configure dynamic updates, or use static IP addresses and manually enter them).

This server resolves dhcp alloted local machines automatically in addition to external hosts, with the added advantage being both dhcp and dns server are allways in sync. Also there is no need to create and maintain cumbersome zone files. Dual DHCP DNS Server is an Open Source Freeware. In addition, this server is designed for Load Sharing Replicated Operation

DNS Features include Forward and Reverse Lookup, Zone Transfer, Primary/Secondary Mode of Operation, MX Records, Wildcard Records, Conditional and Default forwarding.

DHCP Fearures support Static and Dynamic 125 DHCP Ranges, Range Filters, Relay Agents and BOOT, Options can be specified for DHCP Ranges, Global or for Static Hosts.

Either DHCP or DNS Service can be used. If both services are used, DHCP allotted hosts are automatically added in DNS zones.