Domain Name Service
Why Domain Name Service (DNS) and How It Works
This is a basic explanation to help you have an understanding of the DNS system. If you need more technical information refer to the books at the bottom of this page.
Domain Name Service (DNS) is the system by which domain names (like wizardsplace.com) are converted to Internet Protocal (IP) addresses (like 64.123.121.75). It may come as a surprise to some but domain names and URLs (web addresses) like:
http://www.wizardsplace.com/
are not really understood by your web browser or other Internet programs. In order for your browser to connect to, and display, a website it needs to know the IP address for that site and thus find where the website actually is located on the Internet.
URLs and domains names don’t mean anything to computers or programs like browsers. These are for people, like you and me. Your browser needs a way to look up the IP address associated with the domain name. This is where the DNS comes in.
You can think of it a little bit like making a phone call. If you used the letters on the phone to enter my name we wouldn’t likely connect. But if you know my name (Stephen Henry) and the city where I live (Hutchinson, KS) which is my real world location (address), then you can call 411 (directory assistance) to get my phone number to make the call.
The Domain Name service is much like directory assistance for the Internet. Originally there were a handful of primary DNS servers that handled all the work but the Internet grew rapidly and is now very large with billions, perhaps trillions of website connections happening regularly. This amount of traffic requires that there be many DNS servers available to handle the traffic. In fact, today, almost every web hosting site provides two or more DNS servers which update their own information periodically from the primary servers, thus reducing the load on the central system.
The correct DNS servers for your website are provided by your web hosting service. These are the DNS addresses you will enter into the DNS setup on your domain registrar account. Your domain registrar and hosting services may well be at two different companies. This is okay, and it is just one of the reasons why DNS is important; to tie domain names to hosting accounts.
DNS server addresses typically look something like:
ns1.somedomain.com
ns2.somedomain.com
They typically start with NS and a number, though this is not a requirement. The NS part stands for Name Server and the number indicates which one (usually of several) is being referenced.
It may surprise you but when you enter a URL (eg: a website address starting with http://) into the address bar of your browser your browser has no idea which website that URL represents. URLs (and domain names) are words that make a little sense to us — we can quickly recognize wizardsplace.com vs. etsy.com — but not your browser. It’s all just words.
Your browser has to call the Internet directory assistance (DNS – Domain Name Service) and asks for the IP address (phone number) that is associated with the URL (address) so it can connect (make the call) to the website you are asking for.
The central DNS has too much work to do because the Internet is global, so it hands your browser off to a secondary DNS server, one of the two you listed in your domain registrar account. This secondary DNS server knows where your website is located. The person who set up your website arranged for this entry in the local (secondary) DNS. That DNS gives your browser the IP address for the website. IP addresses are something computers can understand. Your computer finds its way through the maze of the Internet using the IP address as a guide (another topic you might be interested in: routing) and the connection gets made. It’s really quite an elegant system.
Problems Changing DNS
The problem is, browsers are lazy and, at the same time, like to impress their owners with how fast they are, so they “write down” any new IP addresses on their note pad (cache) so they can look it up in the future without having to take the time to connect to the DNS servers. You may notice when you go to a new website for the first time it takes a little longer to connect than when you go there later. That’s because your browser already “knows” the IP address and doesn’t need the two or three seconds it takes to look it up through DNS.
But, if we change your website’s location and, as a result, change the DNS servers, the IP address for your website changes and the old one that your Browser has stored in its cache takes you to the wrong place. We need to clear this cache entry in order to force the browser to look up the new IP address.
Some caches clear automatically (or, at least, the individual domain name gets looked up again) on regular intervals, often when something like 4 to 48 hours has elapsed since the last time it was looked up. The browser uses this time interval to determine if it should trust the reliability of the IP address it has cached. We call this time interval the Time To Live (TTL)
Some browsers, like Internet Explorer, have what has come to be called a “sticky cache” and you often have to manually clear the history in order to force a new DNS look up. On some computers, especially if they are part of a local network, the operating system caches IP addresses and they must be manually cleared in order for a new DNS look up to take place. This won’t usually affect the average home business user but it could.
If your cannot seem to find your website after a DNS server change, and clearing your browser’s cache doesn’t fix the problem, contact the Wiz for specific help with your issue.
Books On DNS – This is very technical stuff!
