The great phone book in the sky

Web users should give thanks for humble men with beards and sandals

Sometimes, a system works so well that we barely notice it. Twenty-five years ago this year, the Domain Name System was developed by Paul Mockapetris and Jon Postel. Most internet users will not know what this is, but anyone browsing the web or receiving email is relying on the good functioning of DNS. So, it's worth understanding a little bit about it.

Unlike in the US, we are rarely encouraged in this country to dial 0800 PIZZA or 0845 LAUNDRY when looking for someone to deliver supper or relieve us of our dirty linen. We are quite capable, thank you very much, of managing the strings of numbers that are important to us. Online, the story is different. Browsing the web, we send requests for information many times a day to machines plugged into the network. Each has an IP address - if you're reading this online, you're reading it off IP number But you don't need to know that. When you type into your browser, DNS locates the IP address corresponding to that domain name. Think of it as a great big telephone directory in the sky.

Except it's not in the sky. It's spread across 13 "root servers" around the world. Between them, these servers hold the details of which machine serves which domain name for all 150 million domain names currently registered. Techies and systems administrators know that every time they replace a machine that's serving a website, they need to update their DNS registry. But the rest of us carry on in blissful ignorance, not stopping to wonder why, in the online age, we have not once received a website "change of address" card.

DNS was developed in an age when the internet was conceived of as a useful tool for computer scientists and other academics, an age when real men grew long beards and wore sandals. That it has survived the rapid commercialisation of the web is a testament to the humility of the men who first engineered it - they designed nothing into the system that didn't need to be there. They made functionality their utmost priority.

Now DNS look-ups happen 20 billion times a day. The system has stood up to the technical challenges so far, but there have also been political challenges from the beginning. The recent fight for "control of the internet", played out during the UN-sponsored World Summit on the Information Society, unsuccessfully sought to wrest control of the root servers from what looks like a US-regulated organisation. And engineers have begun to create internationalised domain names in Cyrillic, Arabic and Chinese, which will pose new problems of registry control.

The history of DNS has been one of keeping politics out for the sake of functionality. As you browse the web today, you might like to reflect on this history, and hope that it continues into the future.

Becky Hogge is a writer and technologist. She was formerly the technology director of award-winning current affairs website, and Executive Director of the Open Rights Group, a grassroots digital civil liberties organisation.

This article first appeared in the 11 February 2008 issue of the New Statesman, Now it gets really dirty