DNS on Windows 2000, Second Edition

The Domain Name System, in a Nutshell

The Domain Name System is a distributed database. This structure allows local control of the segments of the overall database, yet data in each segment is available across the entire network through a client/server scheme. Robustness and adequate performance are achieved through replication and caching.

Programs called name servers constitute the server half of DNS’s client/server mechanism. Name servers contain information about some segments of the database and make that information available to clients, called resolvers. Resolvers are often just library routines that create queries and send them across a network to a name server.

The structure of the DNS database, shown in Figure 1-1, is similar to the structure of the Windows filesystem. The whole database (or filesystem) is pictured as an inverted tree, with the root node at the top. Each node in the tree has a text label, which identifies the node relative to its parent. This is roughly analogous to a “relative pathname” in a filesystem, like bin. One label—the null label, or “”—is reserved for the root node. In text, the root node is written as a single dot (.). In the Windows filesystem, the root is written as a backslash (\ ).

Figure 1-1. The DNS database versus a Windows filesystem

Each node is also the root of a new subtree of the overall tree. Each of these subtrees represents ...