Overview of DNS
The Domain Name System (DNS) is the system by which host names on the Internet have domain name addresses (such as abcdef.com) and IP addresses (such as 111.222.33.44).
The Internet, however, is really based on IP addresses. Consequently, the domain name address entered in the Web browser by a user is automatically translated to the numerical IP address for use by the Internet.
The Domain Name System (DNS) uses the DNS service to make these translations or lookups.
To manage these translations effectively, the DNS maintains a database. Each The server in the database is responsible for both name-to-IP-address (forward) and IP-address-to-name (reverse) translations (called lookups).
Thus, no single server or organization site has or owns the DNS information of the Internet. If one DNS server does not know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.
A zone is a section of the domain name space that is represented by the data stored on a particular name server. The name server has authority over that particular zone, or the particular section of the domain name space - described by that data. Each The DNS server manages the lookups for one or more domain name spaces.
Each The DNS server also maintains a list of all domain names and their associated IP addresses. The elements on this list are known as records. Once you have created a zone, you add records to that zone. A zone can contain the following types of records:
Host or Address (A) record: A record that translates each domain name (e.g. you.com) or sub-domain (e.g. abc.you.com) to an IP Address. There should be one A record for each host address.
Alias (CNAME) record: A record that specifies to the DNS server that any requests made to the alias name are to be redirected to the host to which the alias points. The target host does not have to be within the local domain.
Mail Exchanger (MX) record: A record that specifies where the email for your domain name should go i.e. which mail server machine should process the email for that domain.
Name Server (NS) record: A record that specifies the host name of a DNS server that is authoritative for the domain. A DNS zone requires at least one NS record. If there is only one NS record in a zone, it cannot be removed.
Pointer (PTR) or Reverse record: A record that associates an IP address with a canonical name. PTR records are used to convert IP addresses to host names. This is known as reverse lookup.
A Start of Authority (SOA) record contains the information stored in a DNS zone about that zone and about other DNS records. Each zone contains a single SOA record. When you add a zone to a domain, an SOA record is automatically created.
The SOA record:
Designates the start of the zone and specifies where in the domain name space the name server has authority.
Specifies timing information for zone transfers. Zone transfers are usually used by secondary servers to update its own zone data from its primary server.
Provides contact information for a zone. Every zone’s SOA record contains the email address of the zone’s technical contact.