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 Concepts and Operation 1 2 3 DNS Name Server Data Storage: Resource Records and Classes

DNS Server Support Functions

The storing and serving of name data (through responses to requests from DNS resolvers) is the main function of a DNS server. However, other support jobs are also typically required of a DNS server, including the following:

• Interacting With Other Servers: As mentioned above, the DNS resolution process often requires that multiple servers be involved. Servers must thus maintain not just name information, but information about the existence of other servers. Depending on the type of DNS request, servers may themselves become clients and generate requests to other servers.
  
  
• Zone Management and Transfers: The server must provide a way for DNS information within the zone to be managed. A facility also exists to allow a zone transfer to be performed between the master (primary) server for a zone and slave (secondary) servers.
  
  
• Performance Enhancement Functions: Due to the large number of requests servers handle, they employ numerous techniques to reduce the time required to respond to queries. The most important of these is caching of name information. A variation of regular caching called negative caching may also be used to improve performance, and load balancing is a feature that can be used to improve efficiency of busy devices registered within the DNS system.
  
  
• Administration: Various other administrative details are required of name servers, such as storing information about the different types of “contacts” (humans) who are responsible for certain tasks related to management of a domain or zone.

As we'll see later in this section, not all name servers perform all of the tasks described above in this topic; some perform only a subset.

DNS Name Server Concepts and Operation 1 2 3 DNS Name Server Data Storage: Resource Records and Classes