Someone successfully shut down many websites Friday, attacking a crucial part of the internet that has been made more vulnerable due to an Obama administration decision to surrender American control, according to experts. Websites like Twitter, Spotify, Reddit and many others were not working for a large portion of U.S. citizens Friday, after unknown hackers breached the servers of Dyn, a major domain name system (DNS) host. Essentially the “yellow pages” of online addresses, DNS is the technical network that converts web address names into numbers. “We began monitoring and mitigating a DDoS attack against our Dyn Managed DNS infrastructure....