The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. An often used analogy to explain the Domain Name System is that it serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. For example, www.opdubey.info translates to
A Brief History

Fey years ago the ARPANET (Advanced Research Projects Agency) was the Beta of what we know as the Internet. When the ARPANET was running there were a lot fewer computers connected at that time.  Hosts.txt files were used to navigate the ARPANET.

TCP/IP (Transmission Control Protocol/Internet Protocol) was the beginning of what we know today as the Internet. With the new protocol came more computers and more people using them. The Hosts.txt files became extremely inefficient. The biggest problems were traffic, name collisions and consistency. It became necessary for a global database that could route traffic. In 1984 the architecture for what is now DNS was designed. It is a global database of DNS records.

What is a DNS record?

Computers on the other hand don’t really care about names. They would work just find if everything was numbers. Remember back to the Dark Ages of computers and everything was binary (1s and 0s). IP is a series of numbers to identify each computer. It is a logical way of seeing things for computers.

The domain names and the IP addresses needed a common translation process. Since there are thousands upon thousands of computers attached to the Internet, it needed to be in one location.

DNS records are located on DNS servers. They translate the domain name to the IP for every computer. It is done with a Database that is queried all the time. There are thousands of DNS servers across the Internet to support the constant use.

What are the different parts of DNS?

  • A Record – This is the part that translates the domain name to the IP.
  • CNAME – This is a domain name alias. To mask this, CNAME-records can be used to give a single computer multiple names (aliases).
         For example the computer "computer1.xyz.com" may be both a web-server and an ftp-server, so two CNAME-records are defined:
        "www.xyz.com" = "computer1.xyz.com" and "ftp.xyz.com" = "computer1.xyz.com".

  • MX-Record – This record specifically points to your email server (announces a mail exchanger for a domain).
  • NS Record: This is used to specify a zone's primary server and all its secondary servers. An NS record points to a master name server of the given zone, with the resource data field containing the hostname of the name server.
  • PTR Record: This type of record is used to associate names in the in-addr.arpa domain with hostnames. It is used for reverse mapping of IP addresses to hostnames. The hostname given must be the canonical hostname.
  • HINFO :This record provides information on the system's hardware and software.The hardware field identifies the hardware used by this host.