The entire internet of Sweden [".se"] was down for an hour recently:
Royal Pingdom writes of the error: “The problem happened during planned maintenance of the .se domain. The .SE registry used an incorrectly configured script to update the .se zone, which introduced an error to every single .se domain name. We have spoken to a number of industry insiders and what happened is that when updating the data, the script did not add a terminating “.” to the DNS records in the .se zone. That trailing dot is necessary in the settings for DNS to understand that “.se” is the top-level domain. It is a seemingly small detail, but without it, the whole DNS lookup chain broke down.”
http://mashable.com/2009/10/13/sweden-internet-downtime/
