1-11 DNS ConfigurationThis chapter covers only IPv4 DNS configuration. For details about IPv6 DNS, refer to IPv6Management Operation.DNS OverviewDomain name system (DNS) is a mechanism used for TCP/IP applications to provide domainname-to-IP address translation. With DNS, you can use memorizable and meaningful domain names insome applications and let the DNS server resolve it into correct IP addresses.There are two types of DNS services, static and dynamic. Each time the DNS server receives a namequery, it checks its static DNS database before looking up the dynamic DNS database. Reduction of thesearching time in the dynamic DNS database would increase efficiency. Some frequently usedaddresses can be put in the static DNS database.Static Domain Name ResolutionThe static domain name resolution means manually setting up mappings between domain names andIP addresses. IP addresses of the corresponding domain names can be found in the static domainname resolution table for applications, such as Telnet.Dynamic Domain Name ResolutionResolution procedureDynamic domain name resolution is implemented by querying the DNS server. The resolutionprocedure is as follows:1) A user program sends a name query to the resolver in the DNS client.2) The DNS resolver looks up the local domain name cache for a match. If a match is found, it sendsthe corresponding IP address back. If not, it sends the query to the DNS server.3) The DNS server looks up its DNS database for a match. If no match is found, it sends a query to ahigher-level DNS server. This process continues until a result, success or failure, is returned.4) The DNS client performs the next operation according to the result.
