DNS: The Internet's Contact List
How many phone numbers do you know off the top of your head?
These days, probably not many. That’s fine, because on a modern mobile phone, it’s easy to go into a contact list and find the number you need by name. Websites are actually the same way. Each website has a number behind it called an IP address, but instead of memorizing IP addresses, they can be converted into more memorable names using DNS.
DNS, or the Domain Name System, is a universally recognized system that has been in use since 1985. A domain name is divided into parts called labels, each separated by a period.
The most important piece, the top-level domain(TLD), is on the far right. TLDs are officially managed by the Internet Assigned Numbers Authority. TLDs are usually short, with most being 2 to 5 characters long, but can technically be up to 63 characters! As of 2015, the longest TLDs based in the English language are .international for single words only, and .cancerresearch for compound words. Most TLDs are intended for websites dedicated to specific topics, such as .fit(fitness and exercise) or .med(medicine), but some are unrestricted or restricted by intentionally loose terms, such as .com/.net/.org(all unrestricted), or .blue(for “everyone who loves the color blue or wants it to enhance their business or their brand”).
Everything to the left of the TLD is a subdomain of the domain to the right. Example.com is a subdomain of .com, and www.example.com is a subdomain of example.com. Yes, the www does do something, even though it has fallen out of favor in recent years!
DNS works with a series of queries. When you type in www.example.com, the computer asks .com where to find it. .com directs the computer to ask example.com, and it sends you to 18.104.22.168.
This all happens so quickly, you’ll never notice a thing!
And that, is DNS simplified!