Depends on what you are trying to do. Your question is not clear.
Are you trying to provide external DNS services for your own domain? If you have a cable modem or DSL and your provider dynamically assigns you an address, you can NOT be your own DNS provider for your own domain. DNS servers must be hosts with static addresses, since they are registered with the root domain providers and those records are not intended to be updated frequently.
You need an external DNS provider.
If your address changes frequently, Google for a "dynamic DNS provider." Some router/firewall devices can be used with dynamic DNS services, but it's likely that you will need to reconfigure your network with your Linux box taking the place of your router/firewall (you'll need to install a second network card) and install appropriate auto-updating software.
If your address doesn't change frequently, EasyDNS or MyDNS.com will do, and you can configure your router/firewall to redirect well-known ports (such as HTTP and SMTP) to specific internal hosts.
