Configuring Delivery of Fixed Addresses

If you want to run servers but configure them to acquire their IP addresses and other information via DHCP, you can do so. This practice normally requires that you do one of two things, though: •

Link your network's DHCP and DNS servers so that the DNS server delivers the correct IP address for a given hostname. This practice may be reasonably reliable on a local network, but it may not be reliable if your systems should be accessible from the outside world, because your DNS server's entries will be cached by clients' DNS servers. Clients may, therefore, end up using an out-of-date DNS entry. Even if you configure the DNS server with a short lifetime for these entries, some DNS servers may ignore this information, possibly resulting in mismatched hostnames and IP addresses. This configuration also requires making intricate changes to both the DHCP and DNS servers' configurations. For these reasons, I don't describe this approach in this book.

• Configure your DHCP server to assign an unchanging IP address to the server computers. This goal can be achieved in several ways. The method I describe in this section involves using the Media Access Control (MAC) address, aka the hardware address, of the DHCP client computer to identify that system and enable the DHCP server to assign a specific IP address to that system each time it boots.

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