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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 Servers and Name Resolution                           9  DNS Name Server Concepts and Operation

DNS Name Server Data Storage: Resource Records and Classes 1 2 3 DNS Zone Management, Contacts and Zone Transfers

In the first two topics in this section, we have looked at the functions of DNS servers, with a particular eye to the important job of storing name server information. There are many thousands of DNS servers on the Internet, and not all are used in the same way. Each DNS server has a particular role in the overall operation of the name system. The different kinds of servers also interact with each other in a variety of ways that we need to understand.

Every zone needs to have at least one DNS name server that is responsible for it. These DNS name servers are called authoritative servers for the zone, because they contain the full set of resource records that describe the zone. When any device on the Internet wants to know something about a zone, it consults one of its authoritative servers.

From a strictly theoretical perspective, having one name server for each zone or domain is “sufficient” to provide name resolution services for the entire DNS name structure. From an implementation standpoint, however, having only one name server for each part of the name space is not a wise idea. Instead, each zone usually has associated with it at least two name servers: one primary or master name server, and one secondary or slave name servers. Some zones may have more than one secondary name server.

DNS Name Server Data Storage: Resource Records and Classes 1 2 3 DNS Zone Management, Contacts and Zone Transfers