What is DNS?
DNS stands for Domain Name Server. I know the word Server is intimidating and you are thinking “oh sure, another article written in hyper-technical language”. Think of a server as a regular computer, like the one you are using now to read this. That’s right! Your beloved computer can be a server too. We call a computer a server when that machine is up and running and providing a service (“serving” something, whether a web page, a text document, etc.)
IP Addresses – Service Providers – Domain Names – Domain Name Registrars – DNS – The Propagation Process
IP Addresses
Our computers talk to each other by identifying themselves using numerical addresses much like the address on your home or for your telephone. When one computer wants to speak to another computer, it all boils down to an address or what we call an “IP Address”.
Here is an example: 69.247.49.26
As you would imagine, the number of possible addresses, while immense to the untrained eye, is actually limited and we are almost on the verge of exhausting all the numbers…. Here’s a piece of trivia for all interested in cool facts: Typically, service providers (see below) receive thousands of IP addresses to be used on their networks. IP addresses in the United States are assigned by ARIN, the American Registry for Internet Numbers. They are the assigned numbers authority and they control who gets IP addresses in the US.
Service Providers
The service providers will use IP addresses to identify their network equipment so that they can conduct business on the internet.
There are many different types of service providers but for the purpose of this article, I will only discuss two of them.
The ISP (or Internet Service Provider) is the company that provides you with access to the internet. Without them, you would not be able to send email or surf the world wide web. When you connect to your ISP, they will assign your computer one of their IP addresses. This IP address will be used to identify your computer while you are connected to the internet.
Now, let’s summarize what we have learned so far by looking at a typical internet users experience:
Let’s say that you want to surf your newly published website. You connect to the internet and your computer gets an IP address (much like a phone number, a license plate, etc) from your ISP. You then open up your web browser and type in your website’s domain name: yourdomain.com.
Then you hit enter. Your computer sends a request. That request is blasted across the internet jumping through routers and gateways, across wires and beamed to satellites and back down to Earth again. After traveling several thousand miles in just a few milliseconds, it finally arrives at your Web Host’s web server because it contains the IP address of the computer you are looking for.
The server then responds by sending a copy of the website’s home page back to your computer because it knows the IP address of the computer that made the request. You are now looking at your published home page in merely a few seconds and being proud of the pretty colors you picked for your menu buttons.
How did this all happen? Read on:
Domain Names.
A domain name is what you typically enter into your web browser when you want to visit a website. We also use them when sending email.
Website: www.yourdomain.com / Email: user@yourdomain.com
Domain names provide a fast and convenient way of reaching our favorite websites and sending email to each other. It is easy to remember the name of a friend’s website or a company that you like to shop with rather than trying to remember a number like: 64.247.43.26
Also see Domain Info in this site.
Domain Name Registrar
If you want to have your own domain name you will need to register one through a company called a Domain Name Registrar. The domain registrar has tools that allow you to search for and register an available domain of your choosing. The registrar is more or less at the top of the whole naming scheme chain.
If you were able to read this far and even stay focus, congratulations – you ar a very determined individual. And now, as a reward for reading this much of my article, I will talk about… DNS, which is the topic you came here to read about in the first place.
DNS
DNS is a software program that runs on a dedicated computer known as a DNS server. DNS serves two primary functions:
(1) To translate domain names into IP addresses.
It’s much easier to remember a domain like mydomain.com than a sixteen digit number like 64.247.43.26. DNS servers make translating or “Resolving” this information fast and seamless. When your computer needs to know the IP address for yourdomain.com it asks a DNS server (usually the one provided by your ISP.)
(2) To act as authority for designated domain names.
Wherever you decide to host your website, the network you are on must have its own DNS servers. In fact, it is an industry-wide standard to have at least two DNS servers or more. These servers will act as the authority for your domain name because your network provider will put a special entry in their DNS server as it relates to your domain name that says: YOU ARE HERE! Technically this is known as an “A” record for “Authority”.
There are literally hundreds of thousands of these DNS machines world wide. They are the yellow pages of the internet and they contain information about your domain name. Keep in mind that no single DNS server holds all the domain names for the internet; they only hold the names that they are responsible for, and a few pointers to find the rest.
Some DNS servers strictly store names while others are doing the work of providing lookup services for computers that need to look up names. Many DNS servers do both. Technically, the server that is responsible for a particular domain is called the “Authority”. Remember the “A” record?
There are a few pieces of crucial information stored in a DNS server with regard to your domain name. This information as a whole is known as your “DNS Record”. In it you can find a variety of other pieces of information (or records) about your domain name. For the purposes of not altering your sanity, in this article I will focus only on the domain name, the ‘A’ record (or your web host’s DNS servers).
The Propagation Process
As I said before, your domain registrar is the one responsible for publishing your domain name at the very first (called root) DNS level. When it is published, it is placed into a directory that is broadcast out to primary DNS servers around the world.
The primary DNS servers broadcast out to secondary DNS servers and so on and so forth.
This process is known as propagation and it can take upwards of 72 hours to complete. Propagation refers to the amount of time it takes for all the DNS servers everywhere around the world to recognize the fact that either a new domain is being registered, a domain name has been changed, or that the authority for that domain has changed.
Other reasons why it takes so long is obviously the size of our planet and the total number of DNS servers that require updated information. DNS servers are always updating themselves and changing dynamically during the course of any given day. When or why one DNS server will receive updated information before another is a complete mystery – really!
In most cases, your DNS propagation will complete well within the 72 hour period but you can’t be sure that everything is fine until you wait out the 72 hours! I’ve personally found that DNS propagation takes 4 to 6 hours max. Once propagation is complete, anyone, anywhere on the internet should be able to visit your hosted website.
During that time you may experience strange occurrences. This is because not every DNS server that needs to know, knows about your domain name. Take your ISP for example. They use two DNS servers, well, 24 hours after making your nameserver changes, only one of your ISP’s DNS servers might receive the update regarding your domain name and the other might not.
If only one of these servers can resolve your domain to an IP address and the other can not, what you will experience would be as though your website was going up and down. One moment it is there, the next it is not.
If you avoid making changes to your website during a transfer/propagation period, you will always have a consistent functional website available to your visitors. They won’t know that you have switched Web Hosts because as far as they can tell, they are just browsing your website. They won’t realize that you are in a state of propagation and that from one minute to the next, they are potentially browsing your site from two different Web Hosts. It’s one of those rare cases of “what they don’t know won’t hurt them”.