A terrorist would have to understand internet and cyber world before he could pull off an attack. On top of that, he would have to gain a realization that United States depended upon this infrastructure, and then he would have to learn all about it.

We take it for granted because thirteen year olds in United States and Europe create viruses and worms in their sleep. As a security manager for a major company, I see dozens of viruses every single day, so I just assume that other people understand these things. Well, guess what, power of internet is not obvious to ignorant renegade Saudi princes who have been living in wilderness of Afghanistan for most of their lives.

Certainly it is easier for this uncivilized savage, dumber than earth barbarian (Usama Bin Laden and every other terrorist) to make a gasoline bomb than it is to create one paragraph of intelligent writing. Anyone can make a gasoline bomb out of an airplane, and it certainly does not take many working brain cells to crash one into a skyscraper.

You also have to understand that internet was designed and built to survive a major, country-wide nuclear attack. That's a lot more power than any terrorist scum is likely to possess.

Is there a danger of cyber-terrorism? Sure there is. This is a critical piece of world infrastructure and it must be protected, just like any other communication or transportation line.

There is actually more of a danger of cyber-warfare than of cyber-terrorism. Countries do understand value of internet, especially highly civilized nations. Generals and soldiers do understand value of good communications (which is really what internet is all about). One of first and most important tasks of any warmaster is to disrupt communications.

Terrorists do not want to disrupt communications. In fact, that's last thing on their mind, since they survive only as long as communications remain intact. Imagine what would happen to any terrorist whose acts were simply ignored. If no terror resulted, then why try and cause terror? Thus, terrorist targets are specifically chosen to be most visible, and thus most communicated. You won't find many terrorists who bomb isolated targets out in Siberia - who would see it?

That, in a nut shell, is why terrorism never has and never will win a war. They are not playing to win - they are playing to terrify. They do cause damage and they do cause, well, terror - but they do not win.

Attacking via internet might win a war, but it will not cause terror. Thus, it is not a highly tempting target for terrorists. A terrorist attack against it is not impossible, but it is highly unlikely.

Also common is webmaster who does not understand that many servers are case sensitive. This means that "Richard" is not same as "richard". You will see this sometimes if a webmaster moves a site from a server which is not case sensitive (VAX/OpenVMS) to one that is (Unix).

Sometimes a site simply moves to another host. This frequently happens when a site outgrows it's host. I know of one site that had to move several times because it's bandwidth demands became huge! According to webmaster this site was getting tens of thousands of visitors every day, and all of them were downloading tremendous amounts of pictures. He was booted off one server with no notice and no backup and had to rebuild his site from scratch! This kind of event will certainly cause 404 errors!

More rarely, a webmaster has been in process of uploading his site when his upload software crashed. This may leave broken links for a short time until problem is fixed.

Generally an ISP will provide, at least for a short time, a redirect page to a new site. You will see this as a "My site has moved. If you are not transported in 10 seconds click here" message.

And of course some sites simply shut down. This is actually getting more rare as it's often more expensive for an ISP to delete old data than it is simply to prevent updates.

Search engines are notorious for their broken links. You have to remember th at most search engines only examine web sites every month or so (sometimes delay is as long as six months). Because of this, all of above problems can occur, leaving broken links.