Microsoft issued a statement yesterday to say that a technician had made the mistake when changing the configuration of routers for its DNS (Domain Name Server) network. The DNS servers are used to connect domain names with IP (internet protocol) addresses of the various servers and networks that make up Microsoft's web presence. The mistaken configuration change caused many of Microsoft's sites to be unreachable.
Earlier on Wednesday, Microsoft had said that it could not rule out a denial of service attack. Several leading web sites have been the victims of such incidents. These are attacks by individuals who flood a web server with false and untraceable requests for information, overwhelming the system and ultimately crashing it.
The company later said:
“This was an operational error, and not the result of any issue with Microsoft or third-party products nor the security of our networks. Microsoft regrets any inconvenience caused to customers due to this issue.”
The failure of the site is likely to cost Microsoft lost advertising revenue. Its network of sites, including Microsoft.com, Expedia.com, Encarta.com, MSN.com and Hotmail.com, attracted around 54 million US visitors in December, trailing only AOL and Yahoo! AdZone Interactive, an internet advertising company, estimated that MSN.com received $33 million in ad revenues in November and that Hotmail.com received $22.3 million.