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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  Name Systems and TCP/IP Name Registration and Name Resolution            9  TCP/IP Name Systems: Host Tables and Domain Name System (DNS)                 9  TCP/IP Domain Name System (DNS)                      9  DNS Name Registration, Public Administration, Zones and Authorities

DNS Hierarchical Authority Structure and the Distributed Name Database 1 2 3 4 DNS Geopolitical (Country Code) Top Level Domains and Authorities

The top of the DNS name hierarchy is managed by a central authority, which controls the entire name space by virtue of deciding what top-level domains (TLDs) are allowed to exist. Obviously, it is very important that a great deal of thought go into how the TLDs are chosen; a poor design at this top level would make the entire hierarchy poorly reflect the actual structure of organizations using the name space.

There are any number of ways that the creators of DNS could have chosen to structure the Internet's name hierarchy. One obvious possibility would be to structure the Internet based on geopolitical boundaries: countries, states and so forth, as we saw in a topic in the last section. Another sensible idea is to structure the name space based on types of organizations. One could imagine other possible ways to divide up the names of the world's computers as well.

The beauty of the hierarchical name space is that we don't have to choose between different methods of structuring the name space. We can use more than one technique at the same time, and this is exactly what was done when DNS was first implemented. Both of the methods I described above, based on organization type and geography, were used for TLDs. This gives multiple options for name registration for most groups and individuals. I’ll begin here by discussing organizational TLDs; geopolitical ones are the subject of the topic that follows.

DNS Hierarchical Authority Structure and the Distributed Name Database 1 2 3 4 DNS Geopolitical (Country Code) Top Level Domains and Authorities