Special Reports

A brief blackout at internet search giant Google has drawn attention to the creaking addressing system that underpins the worldwide web.

The Google search page disappeared from view for about 15 minutes at 2245 GMT on Saturday, and the company's email and online advertising services also suffered disruptions. Some users reported being redirected to an alternative search service called SoGoSearch, but Google has strongly dismissed suggestions that its servers were compromised in any way.

"It was not a hacking or security issue," spokesman David Krane told Associated Press. "Google's global properties were unavailable for a short period of time. We have remedied the problem and access to Google has been restored worldwide."

Krane added that the problem was related to the Domain Name System (DNS), which maps web names to the numerical Internet Protocol (IP) addresses used by computers. When a web surfer types www.google.com into a browser, a DNS sever tells their computer to connect to a machine with one of several possible IP addresses, such as 66.102.9.104.

Root cause

There are thousands of individual DNS servers dotted around the internet that report back to 13 "root" servers holding master records for DNS mapping. But it remains unclear whether the outage at Google was the result of a malfunction in one particular server or the wider system.

Paul Mutton, an engineer with UK internet monitoring firm Netcraft, says the nature of the outage suggests the DNS server operated by Google itself suffered a malfunction. He suggest that local DNS servers were unable to resolve the name www.google.com because Google’s DNS server was malfunctioning and so instead resorted to trying close matches, such as www.google.com.net, which points to SoGoSearch.

"Their DNS servers simply seemed to break for a short while," Mutton told New Scientist. "They were not hacked and made to point at different servers."

The outage has nonetheless drawn attention to widespread reliance of many web users and services on Google and highlights existing concerns over the stability of DNS infrastructure.

In March 2005, the National Academies Research Council, a US government-backed organisation based in Washington DC, issued a report criticising the current state of DNS infrastructure.