Tech Funda - DNS

Many of us who use the internet know how to configure our ethernet cards/modems.We blindly fill in the values as given to us by the service provider.But how many of us know what each field in ti stands for and wad work is done by it.So appropriately the tech funda of the week is DNS which is one of the fields we fill in the network configuration window..why have i chosen this topic u might ask..answers simple its a very common internet term which very very few ppl know about but use it and its simple to understand it too.

Ill give u an example..each one of u when in organization are given a unique id no. so if ur name is "X" ur idno is 1234.Similarly online we have servers to whom we want to connect..say google or yahoo..but to connect to these servers we need their ip address (127.0.0.1 being an example).There are millions of websites in the world and to remember the ip address of each one would be very difficult so what we do is that we use common names instead of them.Now when we go type some url like www.google.com , this url is fed to the Domain Name Space Server which gives the browser the ip address to which it has to connect too.DNS is like a database in a company where we can get the idnos on inputtin the names.

The following details are technical in nature and wil help u understand the technical aspects of it:

The Domain Name System (DNS) associates various information with domain names; most importantly, it serves as the "phone book" for the Internet by translating human-readable computer hostnames, e.g. www.example.com, into IP addresses, e.g. 208.77.188.166, which networking equipment needs to deliver information. It also stores other information such as the list of mail servers that accept email for a given domain. In providing a worldwide keyword-based redirection service, the Domain Name System is an essential component of contemporary Internet use.

The most basic task of DNS is to translate hostnames to IP addresses. In very simple terms, it can be compared to a phone book. DNS also has other important uses.

Above all, DNS makes it possible to assign Internet names to organizations (or concerns they represent) independent of the physical routing hierarchy represented by the numerical IP address. Because of this, hyperlinks and Internet contact information can remain the same, whatever the current IP routing arrangements may be, and can take a human-readable form (such as "example.com"), which is easier to remember than the IP address 208.77.188.166. People take advantage of this when they recite meaningful URLs and e-mail addresses without caring how the machine will actually locate them.

The Domain Name System distributes the responsibility for assigning domain names and mapping them to IP networks by allowing an authoritative name server for each domain to keep track of its own changes, avoiding the need for a central register to be continually consulted and updated.

A domain name usually consists of two or more parts (technically a label), separated by dots. For example example.com.

• The rightmost label conveys the top-level domain (for example, the address www.example.com has the top-level domain com).
• Each label to the left specifies a subdivision, or subdomain of the domain above it. Note: “subdomain” expresses relative dependence, not absolute dependence. For example: example.com comprises a subdomain of the com domain, and www.example.com comprises a subdomain of the domain example.com. In theory, this subdivision can go down 127 levels. Each label can contain up to 63 characters. The whole domain name does not exceed a total length of 255 characters. In practice, some domain registries may have shorter limits.
• A hostname refers to a domain name that has one or more associated IP addresses; ie: the 'www.example.com' and 'example.com' domains are both hostnames, however, the 'com' domain is not.