(July 23): This column is about those pesky messages from your Internet browser telling you: the "site is not found" or the "server cannot be reached." We all see these more times then we would like to in the course of the day.

Let me start off by saying that although we may feel technologically advanced -- wired and wireless alike -- the Internet is still in its infancy and many of the standard ways of doing things are still being debated and refined.

To the average Internet user, these error messages are just a nuisance. You can't do what you want to do when you want to do it.

To the people who have to deal with these issues -- the tekkies -- error messages like these are another thing to put on the proverbial "bug list."

As with many programs now, these error messages are generic, and most users automatically think the person running that system has messed it up. Sometimes, they have. But that's not true all of the time.

First, some background: There is no central place called the Internet. The term "Internet" refers to the communications links among all of the Internet Service Providers (ISPs) around the world. Locally, an ISP is someone like Midcoast Internet Solutions or Mint.

All of these ISPs connected together make up the Internet. Some provide more access than others, but still they ALL are the Internet.

The Internet uses one important protocol -- the way that things talk to each other -- called TCP/IP to enable all these ISPs to converse. Each computer gets its own unique IP address when it is connected to the Internet. For dial-up users, it gets assigned when you dial in to your ISP, and for people with dedicated connections it is usually assigned until you take your connectivity business elsewhere.

The Internet address (URL) people go to (www.ligature.com, for example) is just an alias for the computer with an IP address (209.222.105.4 in our case)that holds that site. Whether you have a domain name (www.something.com) or not, your computer still communicates on the Internet with an IP address.

Back to those pesky error messages: Often, you receive a message because somewhere the name is not hooking up with the IP address , so your computer can't contact the computer that hosts that site.

That is where "name servers" come in. They hold the information that tells your computer what IP address www.ligature.com has. This information is held in the ISP's name servers. When you ask your computer to go to a Web site, it asks the name server what IP address matches that domain name.

Some ISPs cache (store) that information. This means that instead of always asking another computer what the IP address is, it holds onto that information itself. This means you can browse the Internet faster.

Sometimes, when an Internet Service Provider changes the IP address on the server, the information doesn't get updated everywhere it is stored or cached. When that happens, your computer tries to pull up the wrong IP address to get to a site. It's kind of like a change of address form that gets filled out at the post office; the mail system has your address but you may have forgot to send a form to your Aunt Millie in Peoria.

With communication the way it is among ISPs in Maine, we can usually straighten things out once we know about the problem. Major ISPs (Time-Warner, AOL and so on) are harder to contact, however, so relaying the information to the right person is that much more difficult. Remember, we're still really in the infancy of this technology.

Another reason for the error messages is the equivalent of the old Maine saying "You can't get there from here." In the sense of the Internet and its structure, sometimes communications links just plain go down. When that happens, the ISP you dial in to either can't query to find the IP address, or it just plain can't get the IP address it's looking for.

Most ISPs, Ligature.Com included, monitor things like that so we know when a problem pops up. We also maintain a history of these minor issues, since they might be leading up to a semi-major or major issue.

Finally, there's always the possibility that the machine that hosts your site has crashed (although that gets more and more unlikely as technology advances). However, the host machine may have been taken off-line on purpose, for routine maintenance, for example.

You're most likely to run into that situation in the middle of the night. We tekkies try to take servers off-line during times when the least amount of traffic will be affected...anyway, aren't you supposed to be asleep at 1 a.m.?

Ryan Connon is the Systems Administrator for Ligature.Com in Camden; his columns will be a regular feature at Ligature.Com. Please feel free to email him with any questions, comments, and ideas for future columns.