Domain Name System concepts

Domain Name System (DNS) is a distributed database system for managing host names and their associated Internet Protocol (IP) addresses. Using DNS means that people can use simple names, such as www.jkltoys.com, to locate a host, rather than using the IP address (xxx.xxx.xxx.xxx).

A single server might only be responsible for knowing the host names and IP addresses for a small subset of a zone, but DNS servers can work together to map all domain names to their IP addresses. DNS servers working together is what allows computers to communicate across the Internet.

DNS data is broken up into a hierarchy of domains. Servers are responsible to know only a small portion of data, such as a single subdomain. The portion of a domain for which the server is directly responsible is called a zone. A DNS server that has complete host information and data for a zone is authoritative for the zone. An authoritative server can answer queries about hosts in its zone, using its own resource records. The query process depends on a number of factors. Understanding DNS queries explains the paths a client can use to resolve a query.

• Understanding zones
  Domain Name System (DNS) data is divided into manageable sets of data called zones. And each of these sets is a specific zone type.

• Understanding Domain Name System queries
  Domain Name System (DNS) can resolve queries on behalf of clients.

• Domain Name System domain setup
  Domain Name System (DNS) domain setup requires domain name registration to prevent others from using your domain name.

• Dynamic updates
  i5/OS^® Domain Name System (DNS) based on BIND 8 supports dynamic updates. These allow outside sources, such as Dynamic Host Configuration Protocol (DHCP), to send updates to the DNS server. In addition, you can also use DNS client tools to perform dynamic updates.

• BIND 8 features
  Besides dynamic updates, BIND 8 offers several features to enhance performance of your Domain Name System (DNS) server.

• Domain Name System resource records
  Resource records are used to store data about domain names and IP addresses. This topic contains a searchable list of resource records supported for the i5/OS operating system.

• Mail and Mail Exchanger records
  Domain Name System (DNS) supports advanced mail routing through the use of Mail and Mail Exchanger (MX) records.

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