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Static IP's and DNS Settings

     - Saturday, February 25, 2006

Using static IP addresses on your LAN is both convenient and necessary if you're forwarding incoming traffic to specific machines. Makes sense that you want the target machine to have a known internal IP address. What to set as the DNS address isn't as clear.

You could figure out what DNS address your gateway router is using, and use that. But since the gateway's WAN IP address (and thus the DNS address) is usually dynamically assigned, there's the possibility that your ISP's DNS address might change. Which would leave your machine with the wrong DNS address. Not ideal.

However, our reason for using a static IP address had nothing to do with the DNS. In fact, having the DNS address dynamically assigned would be fine. Unfortunately, if you specify a static IP address, you must also use a static DNS address.

The solution? Use your router's address as your DNS address, and let your router forward the DNS query on to it's WAN DNS address. You'll need to enable the DHCP option on your router. You might also need to select a static IP address that is within the range of dynamic IP's that the router is handing out.

posted by Kevin Watts |  Permalink |