Millions of users around the globe could not access YouTube for a couple hours yesterday. Why?
Well to understand, we need to start with how you normally connect to a web site. You click on a link to youtube.com. Your ISP looks up the internet address for youtube.com by looking at internet routing tables. Each domain has a name server that provides the IP address for where it should be found (for example, an IP address that shows youtube.com is 208.65.153.238).
Well what happened in this case is Pakistan decided to prevent anyone in Pakistan from accessing YouTube because the government didn’t like some video. The way Pakistan decided to accomplish this was to update their routing table to just direct all traffic that was meant to go to YouTube to a phony address which would then return nothing.
Why did many outside of Pakistan lose access to YouTube? Well their version of the routing table leaked out of Pakistan through PCCW (large internet provider), Then other internet providers adopted the incorrect information, until many around the globe were being directed to the wrong place.
You might find it amazing the routing system could allow such a thing to happen – it doesn’t seem very secure. You are right, that it doesn’t seem very sensible. When the internet was created some protocols were established that made sense then but don’t necessarily make sense for what the internet has become.
The problem was fixed when Google’s YouTube engineers contacted PCCW to inform them of the problem and have them correct it. I think if it was my site instead, I would have had difficulty figure out what was going on 🙂 Once PCCW corrected their routing tables the fixed flowed through the system and everyone was able to see the great stuff like Marissa Mayer discussing Innovation at Google.
I would imagine Internet2 (well on its way to a computer near you) and IPv6 will take not be so venerable to such a mistake.
Related: Insecure routing redirects YouTube to Pakistan – YouTube outage blamed on Pakistan – YouTube Censorship Sheds Light on Internet Trust – The Web is 15 Years Old – Internet Undersea Cables – Harvard Course: Understanding Computers and the Internet – Net Neutrality – The Next Generation Internet – The Journey of Internet Packets – mistake proofing (the opposite of the current setup)


