DNS

DNS stands for Domain Name Systems.It is a heirarchical name given to anything on the internet which may be a computer or a resource or a service.It gathers the information that is associated with a particular Domain Name. This used for addressing and locating purposes using numerical or binary identifiers that represent devices on a network.The humaly meaningful domain names are converted to these numerals.The DNS converts the humanly host names given to computers to IP addresses that are identified on the internet with their location.

The Domain Name System helps to give names called Domain Names to different users on the internet. Also these names are independent of the physical locations of the internet resources. It is easier to remember and use these domain names for common people than using IP (Internet Protocol) Address which are difficult to remember as they are not meaningful like the domain names. You need to remember only meaningful URLs and email adress which you prefer and nothing about its location.

The IP addresses are location dependent that is they are alloted according to their physical location. Thus the Domain Names also makes the resource names on the internet consistant because if the resource is located on a mobile server it need not change its domain name when changing its location.

The DNS assigns Domain Names and maps them to IP network by giving authoritative name servers to domains. The DNS not only provides a distributed keyword based redirection system, it also stores related informations like list of mail servers of that domain. The DNS provides technical details of the database of the service by defining a DNS protocol that specifies the data structures and communication exchanges used in the Domain Name Service in detail.

The Domain Name Space has a tree structure having a number of domain names. The leaf nodes in the tree hold the information associated with the domain names. The root of the tree is called root zone which splits into different zones.A DNS zone consists of a group of connected nodes authoritatively which is served by an authoritative nameserver.

The Domain Name has got minimum two parts called a label usually separated by a dot.

Rightmost label gives top-level domain like com for www.abc.com or org for www.abc.org.

Going leftwards gives sub-domains. For example abc.com is a sub-domains for com and www.abc.com is a sub-domains for abc.com.

A hostname is one that has either one IP address or more associated with it.

The DNS is maintained using a distributed database. This uses a client server model. Name servers are the nodes of this database. Every domain or sub-domain are associated with its authoritative DNS server or servers. These DNS servers store information about the domain and its subordinate domains' name servers. The root name servers is topmost in the heirarchy. When looking-up, topmost level is queried first.