Just taking duffbeer's answer a little further - dnsmasq is a very useful tool - though not necessarily what every router uses. Its not exactly clear whether you're just trying to get your own setup working or create a packaged solution for use by other people.
If you want to hold the DNS info on the server, then that implies that you also need to either reconfigure every client to use the server for DNS, or provide DHCP from the server. The latter implies that you'd need to disable (or restrict) DHCP on any pre-existing router.
Either approach entails that you need to provide information to the installers of how to configure any router!
Given that most sensible Operating Systems (including Centos) can provide all the services of a router, and that in some cases, users may be using a cable modem or other such device which is not a router, it would perhaps be more sensible to make the default setup of the server as an internet gateway, with an option of running a DHCP server - and if the user already has a router, then provide a couple of simple programs downloadable to USB/CD which add the device to the client hosts file.
If you just want to get it up and running on your own network, then the solution would be to run DNSMasq on the server or use the facilities of the router or add an entry to the hosts files on the clients.