DNS on Windows Server 2003, 3rd Edition

Checking That Your Network Is Registered

Before proceeding, you should check whether or not your IP network or networks are registered. Some registrars won’t delegate a subdomain to name servers on unregistered networks, and network registries (we’ll talk about them shortly) won’t delegate an in-addr.arpa zone that corresponds to an unregistered network.

An IP network defines a range of IP addresses. For example, the network 15/8 is made up of all IP addresses in the range 15.0.0.0 to 15.255.255.255. The network 199.10.25/24 starts at 199.10.25.0 and ends at 199.10.25.255.

A Sidebar on CIDR

Once upon a time, when we wrote the first edition of this book, the Internet’s 32-bit address space was divided up into three main classes of networks: Class A, Class B, and Class C. Class A networks were networks in which the first octet (the first eight bits) of the IP address identified the network, and the remaining bits were used by the organization that was assigned the network to differentiate hosts on the network. Most organizations with Class A networks also subdivided their networks into subnetworks, or subnets, adding another level of hierarchy to the addressing scheme. Class B networks devoted two octets to the network identifier and two to the host; Class C networks gave three octets to the network identifier and one to the host.

Unfortunately, this small/medium/large system of networks didn’t work well for everyone. Many organizations were large enough to require more than a Class ...