DNSDNS stands for Domain Name System, an Internet protocol that translates computer names into numeric Internet addresses. Every time you're on the Net using e-mail, ftp, or Telnet, you're also using DNS. Without DNS, Netsurfers would have to remember long series of numbers (like 128.56.78.342) to get to a specific site on the Net.
DNS was created basically because of the Internet's growth. When the Internet was smaller, all of the servers simply had a file listing the other servers. With the Net's current size, however, such an approach would be incredibly slow and unwieldy, so DNS was developed as a solution. DNS lets computers find out Internet addresses through the use of a name server (a service in a network that lets you name objects or resources and share this information), linking servers together so that they all have access to each others' information. DNS, which uses a client/server mechanism, works hierarchically; a few "root" servers assume the responsibility for tracking the top-level domains. The root servers know which server has the authoritative information on which servers exist, meaning that through the root servers, you can always find out if a specific address actually exists. For more detailed information on how the addresses in DNS are created, see the "Internet" definition.
When DNS was developed in 1984, its most important goal was to create a consistent name space for referring to Net resources. Its invention made navigating the Net much simpler, since it converts the numerical addresses that computers use into words that are easier for humans to remember. Every Internet site has an entry in a DNS server; a machine is not recognized as part of the Internet unless it has a DNS entry. When sites are updated or eliminated, the site simply makes the change into their portion of the database and everyone can see the change. DNS can be thought of as a type of address book for the Internet. Just as you may have a letter returned because the intended recipient is no longer at the address, so you may receive a "No DNS entry" message while Netsurfing. This message simply means that the computer to which you are trying to connect no longer has information in DNS.
When you request a DNS, you usually receive a response within a matter of a few seconds. During that time, this is what is happening: The DNS server checks its information and sees if it has the IP address. If it doesn't have the address, it redirects your request to the root servers at the top, which in turn check their information. The functioning of the Net rests upon this sequence.
Since each Internet site must administer its own DNS, the Net's recent growth has encouraged the development of more user-friendly DNS services. Companies that do not have an administrator trained in DNS can now hire other companies to handle the DNS configuration. There are also DNS systems that make it possible to set up an Internet server without learning UNIX. DNS 1.1 for Microsoft Windows NT and DNS Auto Pilot are examples of these. BIND is DNS server implementation that is freeware on the Net as well.