From http://blogs.ittoolbox.com/eai/implementation/archives/bell-canada-suffers-major-hosting-outage-10432 :

On Sunday evening (July 9th) it would appear that one of Canada’s largest shared hosting operators – Bell Canada – had a major outage to their shared web hosting infrastructure.  Their shared web hosting environment consists of 4 very large servers.  Two of those servers are known as bellhosting and the other two are known as bellwebhosting.  It would appear that somehow a routing block was created in the core router resolution of the bellhosting pair which caused 100s of websites to disappear including any associated e-mail and ftp services.

The duration of the outage was close to 24 hours before all sites were returned to service.