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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

DNS Name Servers and Name Resolution 1 DNS Name Server Functions, Name Server Architecture and General Operation

Of all the components and functional elements that combine to form the Domain Name System, DNS name servers are arguably the most important. These servers, which may be either dedicated devices or software processes running on machines that also perform other tasks, are the workhorses of DNS. They store and manage information about domains, and respond to resolution requests for clients—in some cases millions of times each day. Understanding how they perform both this most basic task and the many support jobs for which they are also responsible is crucial to understanding DNS as a whole.

In this section I describe the concepts related to DNS name servers, and explain how they operate. I begin with an overview of DNS name server functions and general operation. I describe the way that DNS name server data is stored in resource records and the role of classes. I discuss the different roles of name servers in DNS, and explain the all-important root name servers. I discuss how DNS zones are managed, the notions of domain contacts and zone transfers, and how caching and load balancing are used to improve efficiency in DNS. I conclude with a brief outline of two enhancements to basic DNS server operation, using the new Notify and Update message types, as well as incremental zone transfers.

DNS Name Servers and Name Resolution 1 DNS Name Server Functions, Name Server Architecture and General Operation