To start with, you need to know that every computer on the Internet is assigned an IP address. That is, a series of four numbers, separated by periods. These numbers make up the actual address of the computer. For instance, the main Web server at Ancestry.com is at 216.10.103.21. (That’s the address at this moment; Ancestry has multiple servers, and you might be connected to a different one.) You probably are used to typing www.ancestry.com but you can go to the same server by typing the following into your Web browser: 216.10.103.21.

Domain names are simply easy-to-remember names, or "handles" that are used in place of addresses. In fact, whenever you type a domain name, such as www.ancestry.com, into your Web browser, a behind-the-scenes look-up takes place and then your Web browser automatically makes a connection to the numeric address. This is all done without your realizing it. The systems that make all this work are collectively called DNS, or Domain Name System.

The DNS process is similar to a telephone book. For instance, you might not know John William’s telephone number, but you do know his name. You dig out a telephone book, look up his name and find the telephone number associated with his name, and then you dial that number to be connected to John Williams’ telephone. DNS works in a similar manner although the lookup process normally is invisible to you. When you type www.ancestry.com in your Web browser, the browser queries DNS. DNS associates the name with its number and returns an IP address of 216.10.103.21. The Web browser then "dials" (connects to) 216.10.103.21.

Lists of domain names and IP addresses are distributed throughout the Internet in a hierarchy of authority. You probably are using a DNS server belonging to your Internet provider. That DNS server only holds a fraction of the addresses (like a local telephone book), but it also has pointers to other DNS servers that hold more entries. If your Internet provider’s DNS server can map the domain names in your Internet requests to the corresponding IP addresses, it completes the job by itself. However, when it does not locate a name you entered, it forwards the request to other servers in the Internet.

It is possible to have your home Web server mapped into the Internet’s DNS servers so that you can be assigned a name that will be translated into a numeric IP address. A problem arises, however, because IP addresses on home computers normally change frequently. Ancestry.com has a permanent IP address of 216.10.103.21. Likewise, most corporations use permanent IP addresses.

Home computers normally do not have that luxury. As I wrote last week:

Your IP address is not under your control; your Internet provider assigns it. Keep in mind that your IP address may change often. Many Internet providers will change your IP address for you automatically every day or every week. Others may leave it alone. Also, every time you re-boot your system, you may be given a new IP address. Most Internet providers use dynamic IP addresses that can change on every re-boot.

You may have to tell your users about your new IP address every time it changes, not a convenient solution.

Luckily, there is an easy way to have a permanent domain name assigned to a changing IP address. With a permanent name, your users do not have to keep track of changing numbers; they only have to remember the name. For instance, my in-home Web server presently is at 24.240.176.181, but that address will change frequently. Yet all I do is tell my users to connect to www.roots.d2g.com and they can then connect to my in-home Web server. They do not need to remember the numbers, and I do not have to tell everyone when my IP address numbers change.

In order to obtain a domain name that is mapped to a changing IP address, you need to use a third-party service that provides DNS services. These companies will monitor your computer’s changing IP address and then map that address into their DNS servers, changing your IP address listing every time your computer gets a new IP address assigned. It really is simpler than it sounds.

There are several companies that provide services to allow changing IP addresses to be mapped to permanent domain names. The two best-known ones are TZO at www.tzo.com and DNS2GO at www.dns2go.com. Both have a variety of services to offer. I would suggest that, after you read this article, you investigate both of them before choosing these services. TZO’s basic service costs $25.00 a year, while DNS2GO offers a similar service at no charge. Both companies also offer additional services for a fee. I like free, so I elected to use DNS2GO.

DNS2GO has automated programs for Windows, Linux, and FreeBSD. The company also offers a Web-based service that will work on Macintosh and other operating systems, although with reduced functionality. I will describe the Windows implementation although the Linux and FreeBSD versions reportedly are similar.

After signing up for DNS2GO’s free service, you must download a small program from DNS2GO’s Web site and install it. This program automatically loads when you boot your system and sits in your System Tray (the bar at the right-bottom of your screen). It monitors your Internet connection and your assigned IP address. Every time the IP address changes, this small program automatically notifies DNS2GO’s DNS servers of the change. The small program also polls DNS2GO’s DNS servers frequently to report that your system still is online and available. The DNS servers at DNS2GO will automatically map connection requests for your domain name into connection requests for your current IP address.

DNS2GO assigns domain names as a subset of d2g.com, a domain name they own. You must use "d2g.com" as the last part of your domain name, but you may select any word to be placed in front of "d2g.com" as long as that name is available. For my use, I selected "roots.d2g.com." Anyone who now types www.roots.d2g.com into their Web browser gets connected to a tiny PC in my home, assuming that my system is powered up and connected to the Internet via my cable modem. Obviously, if my system is powered down, the request goes unfulfilled - although DNS2GO has some extra-cost options that you may elect which will re-map the request to another Web server of your choosing. For instance, you could re-map to a page that says, "System not available right now, please try again later."

I have been using DNS2GO for about four months now and have found it to be very reliable. To my knowledge, it has always worked when anyone tried to connect to my home computer. While I have described DNS2GO for use with a Web server, it also works with FTP servers, e-mail servers, Internet gaming servers, video conferencing, and remote access. I use PC-Anywhere to connect to my home computer from my office or from hotel rooms when I am traveling. I simply tell the remote PC-Anywhere program to connect to roots.d2g.com. I can then operate my home computer as if I was seated in front of it, even though I may be thousands of miles away.

I hope these two articles have planted a few seeds in your imagination. Today’s technology allows you to easily make your home computer available online for others to use, for purposes of your choosing. After all, you are the system administrator. You choose who can access the system and what they can access. You can share as much or as little as you wish. I would suggest that sharing information online is an excellent use for your home computer.

• Read the next article in this issue.
  
• Return to the previous article in this issue.
  
• Return to the Table of Contents