An unprecedented Amazon Web Services outage that caused nearly 150 major sites and apps – including Snapchat, Venmo and Roblox – to go dark was apparently caused by a common tech glitch.The 15-hour outage appeared to be caused by an “underlying DNS issue,” Amazon Web Services said in a status tracker on its website.It started with an error in its Domain Name System at Amazon’s Virginia data center. Its oldest and largest data plant is located in so-called “Data Center Alley,” alongside hundreds of other pow ...