So most people these days have heard of  .com.   You’ve probably used  .org and .net as well.   But have you heard of  .info, .mobi or .tv yet?   If not, you will!  All of these are valid “top-level” domains (TLD) gaining in popularity and I’d like to provide a quick history lesson on how these generic codes came to be.

A long time ago when the Internet was barely more than a U.S. Department of Defense research project, only a single TLD called .arpa existed.    ARPA stands for “Advanced Research Projects Agency“, or as they’re more commonly known: “the group of smart guys that figured out how to build the Internet”.   This aptly-named .arpa TLD was used to migrate the first domain names off the old non-hierachical ARPANET to the shiny new Internet.   Luckily, new TLDs were eventually introduced, because “ebay.arpa” and “google.arpa” just don’t have the same ring to them.  Nonetheless .arpa is still in use today by computer network geeks like us even though we changed what it stands for (address routing & parameter area—told you it was geeky!)

Throughout the 1970′s and 80′s, the responsibility of managing the new Internet’s domain names fell loosely to university labs in California, the U.S. Military, and eventually a company called Network Solutions.   During this tumultuous time, the standards for requesting new TLDs and keep track of who was using what was a bit shoddy, as valid TLDs were loosely grouped into three categories:  Countries, Categories, and Multiorganizations.   Not surprisingly things got messy.  For instance, in the early 1980′s, NATO was upset that there wasn’t a sufficiently international-themed TLD for their organization, so .nato was created.   In fact during the 1970′s – 1980′s, the various managing organizations were creating TLD’s that weren’t so generic.   Can you imagine having a “.ibm” and “.yahoo” and so on today?   Clearly there needed to be a standard solution as commercial interest in the Internet was growing.

In order to fix the problem the U.S. National Science Foundation decided to hold a bidding competition in the early 1990′s for three different aspects of  managing domain name data:

• Registration services, so people could “sign up” for domains in a standard way
• Information services, so there was an organized method to know who owned what
• Directory and Database services, so there was a way to store and look up that data.

The contract was awarded to Network Solutions, General Atomics, and AT&T respectively  and the collaberative organization known as InterNIC was born.  This was a huge leap for today’s Internet, as it made it much easier for people and companies to “get online” with their own unique domain name since things were more organized under InterNIC.   Many old-timers  (I’m that old) remember a time when you had no choice in registering a domain.  Everyone had to use Network Solutions!

Finally in 1998, a few folks at AT&T forgot to look at the expiration dates on their contracts and AT&T bowed out of managing their piece of the puzzle.   This was a big turning point because the U.S. Government also wasn’t very interested in managing the Internet any longer.  So instead of the U.S. Government taking on the job on directly,  InterNIC was folded under a new non-profit company called ICANN.   Contracted by the U.S Commerce Department, ICANN decides things like what new TLDs are deemed worthy.   This is currently how it stands today, and InterNIC still provides that service as a subsidiary of ICANN.

Also under the management of ICANN, another big change occurred.   Now any organization with sufficient worthiness (and many papers signed) could register domain names under the existing and established TLDs.    This opened the doors for places like The Linux Fix to register domain names on behalf of their customers and make the whole process much easier for the average person.   Obviously this has had a sweeping effect on the Internet by putting a globally-accessible domain name within reach of anyone.

And there you have it!   The brief and amazing history of the Internet domain name.   Oh, and perhaps you’re now wondering what all the valid TLDs are?  Here you go!

DNS In a Nutshell

The Domain Name System (DNS) is simply a Internet-wide database for associating friendly domain names (example.com) to an IP addresses (1.2.3.4). Over time, other functions such as Domain Keys and SPF for Spam prevention have burdened DNS with a few more responsibilities–but none have fundamentally changed its primary purpose or how the system works.

The Players

To understand the DNS process one must understand the parts involved, and fortunately DNS only has a few.  On the Internet, the DNS system can most generally be segmented into three major parts:

1. Your computer.
2. The Root DNS Servers.
3. All other DNS Servers.

A few important things regarding domain names you should know…

1. The period, or “dot” in domain names is a symbolic character representing a change of authority.  For instance, one server may be responsible for the DNS database containing tlfhosting.com., and yet another might be responsible for linuxrocks.tlfhosting.com. Each time a period is seen by your computer, it knows it has to ask a server for more information.   It could be the same server, or a different one–but it is required to ask nonetheless.
2. Your computer actually “reads” domain names from right-to-left (backwards of how english is read).  Why?  It’s simply trade-off between readability by people and a logical hierarchy that computers need.   Things wouldn’t make much sense to people if we typed .com.tlfhosting.www after all.  It just looks strange, because we read things from left to right.   Yet because of how DNS is structured, your computer needs to read it that way.
3. Every domain name actually has a trailing period.  Notice how we’ve been typing “tlfhosting.com.”?  That’s actually the correct way to type it.  In fact, open a new window in your browser and type www.thelinuxfix.com. (with the trailing period).  Next try www.google.com., or any other domain for that matter.  Normally it isn’t needed, but only becase most software ‘types’ the trailing period for you automatically.  But why the trailing period?  Think of it in context of items #1 and #2 above, and it begins to make sense.

Let’s take a quick look at one of our own second-level domains (we’ll help explain that term in a moment): tlfhosting.com.   Let’s say you’d like to connect to www.tlfhosting.com. to do something–could be a website, telnet, FTP, or anything.  The important point is that to do anything your computer first needs the IP address of www.tlfhosting.com., since it cannot do a single thing with english words!

The Root Servers and TLDs

To get things started, we’ll have to talk about that all-important trailing dot on “www.tlfhosting.com.”

Remember point #2 above.  The first thing your computer sees when trying to translate the domain name is a period (.).  Because of that, it knows a domain is coming next so it will need to ask a DNS server about it.

But wait, which server?  How is it supposed to know where to look if it’s just getting started?

This is where the Root Servers come in.   The Root Servers are represented by the trailing period (.) in google.com. and tlfhosting.com., or any domain for that matter.

As you’ve probably figured out, the Root Servers are then responsible for all top-level-domains (or “TLDs”), such as “net.”, “org.”, “edu.”, and so forth.  They’re called top-level simply because all other domains (like tlfhosting) are under their authority.   So these things are not only busy–they’re very, very important to the operation of the entire Internet!

The Root Servers don’t change much at all.  In fact, most computers are already hard-wired in a programming sense to know who to ask about “com”, “net”, or any of the other TLDs.  In fact, every computer that asks something about any domain name on the Internet at some point or another asked the Root Servers a question. As you can imagine, these are busy little servers.

Now hopefully the term “Second-Level-Domain” should begin to make more sense as well.   If “.com” is a top-level domain, then logically tlfhosting.com is a second-level domain, and thus subdomain.tlfhosting.com would be a third-level domain.  It just goes right-to-left as we were talking about.  Easy as pie!

Keep an eye out for part 2, where we’ll discuss the exact process a computer follows to determine the IP address of any domain.