The BBC is reporting that a censorship action by Pakistan led to a two hour YouTube global outage tonight. The BBC suggests this was possibly an attempt to keep Pakistanis from viewing YouTube videos that showed Danish cartoons deemed offensive to Islam, or a movie clip deemed offensive to Islam.

Google owns YouTube, and engineers there appear to have determined that the ISPs action corrupted the global DNS routing tables, making the site go dark for the entire world rather than just Pakistan ISPs.

Although the action is considered to be a mistake by the ISP, what remains of some concern is the degree to which sites appear vulnerable to actions by ISPs that are completely outside of their control. The DNS system represents a key aspect of the internet and appears more vulnerable to manipulation than many had thought.