Last week, the internet faced its most powerful challenge.

As the World Trade Centre crumbled under a terrorist onslaught and the Pentagon reeled from the worst attack on American soil since Pearl Harbor, Americans all over the world reached for their computers for reassurance loved ones were safe and well.

Network gridlock occurred as millions worried users simultaneously sent email and tried to access online news bulletins.

The problem was the sheer number people involved in the disaster.

The World Trade Centre offered a 16-acre office complex, with approximately 12 million square feet office space, including the two destroyed 110- storey office towers, 47-storey office building, two nine-storey office buildings, an eight-story US Customhouse and 22-storey Marriott hotel.

According to promotional materials, the daily population the World Trade Centre was about 40,000 workers with more than 100,000 visitors and tourists.

Major local phone companies and wireless carriers said a phenomenal number of phone calls had blocked hundreds of thousands callers from connecting with family, friends and work colleagues.

Unable to connect via wireless and landline phones, many New Yorkers posted messages on web sites, signed on to instant chat services and used email in an attempt to contact their loved ones.

Some worried New Yorkers even set up personalised web sites so friends and family could contact each other.

Other New York residents who couldn't get to traditional news sources over a PST line accessed internet relay chat (IRC), to find video footage of the plane crashes and get information about events.

Already people have set up a number of discussion groups using IRC including: Worldtradecenter, Wtc and Terrorist-moderated.

Free messaging services from Yahoo! and America Online (AOL) experienced a huge increase in demand as people tried to contact missing friends and relatives.

A Yahoo! representative said the company's network had experienced an unprecedented increase in traffic and had added more servers to handle the load.

AOL said it had seen a "small spike" in instant chat usage.

The rush to find alternative modes of communication was partially the result of the loss of cell-phone service in much of New York City after the attack.

Some cell-phone carriers sent SMS text messages to all their clients asking them to use alternative methods to communicate so emergency services would have clear airspace.

A leading New Yorkbased service provider, VoiceStream Wireless, requested customers to use text messaging so they would not block the network used for voice calls or emergencies.

Email was the preferred communication tool. Unfortunately, the unprecedented demand for network services effectively clogged the arteries of the internet and caused several services to fail.

Although the internet now appears to be back to normal, some experts are expressing grave doubts about its inherent strength and stability.

The long-term effects of the World Trade Centre disaster are not yet known.

It may take several months to uncover latent system failures.

Many systems engineers have already begun designing and building even more robust networks that will withstand a far greater catastrophe.

Good news for the digerati at a time when pundits are predicting worse is still to come.

Bad news for the world in general. We have seen enough terrorist destruction to last us