A Simple Introduction to DNS

by Terry Stokes

The internet works because every computer that is connected to it, all use the same protocol to communicate and to route traffic. Without this universal protocol the networks that make up the internet would not be able to route the information to the correct destination.The TCP/IP protocol that deals with the way information is shared across the internet is one of the oldest and certainly one of the most reliable. The numerical address of the protocol is what is known as the IP address of the computer, and every machine is given a unique number when they connect to the internet. This gives us humans the main pitfall of this long established system; we find it hard to remember numbers.As humans we like to give everything a name, to help us identify things and recall them later and it is much easier to remember an alphanumeric name than a series of numbers. A good analogy of this is with a public telephone directory, where we look up a name to get the corresponding telephone number, imagine how it would be to remember a number and look up the corresponding name. That is exactly what the DNS system does for us.At its most basic the Domain Name System is ways of giving each numeric IP address an alphanumeric name, for example an IP address may look like 80.145.35.10 but the domain name may look like tasnet.co.uk. The domain name is made up with a hierarchal structure each part is used to speed up the identification of the IP address. The domain name works in reverse with the last part being the first looked at by the DNS system A Domain Name will consist of two or more words separated by a “.”. For example: yourdomain.com the first part “yourdomain” is called a second-level domain. The second part .com is called a top-level domain. A TLD is the suffix that is attached to the end of a Domain Name .com, .net and .org are Top-Level Domains in the hierarchical domain name system. How domain names work is a whole tutorial on its own.So what happens when a domain name is entered into a web browser? The browser sends a request to the closest DNS server to look up the IP address (numeric address) from the domain name (alphanumeric address) and the DNS server sends the information back to your browser, telling it the IP address of the computer the browser needs to request the information from. If the closest DNS server cannot resolve the query the Domain Name System passes the request onto the next server and so on until the information is found and passed back to the browser. If the information cannot be found on the DNS servers the browser will display an error message that says the page cannot be displayed.Each domain name is given an IP address to go to by creating or amending the DNS settings of the domain name with a management tool. Normally this is with an online control panel which allows DNS settings to be changed. These can be changed and this information is distributed to all the DNS servers around the world, this is known as propagation.The DNS settings also control the other uses for the domain name such as the mail servers, but that is for another day

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