Dozens of major websites — including The New York Times, CNN, Reddit, Spotify, Twitch, GitHub, gov.uk, Hulu, HBO Max, PayPal, Vimeo, Shopify — were beginning to return online Tuesday morning after crashing in an apparent internet outage.

What's happening: The cause of the massive outage was not immediately clear. Fastly, a popular content delivery network (CDN), confirmed it was experiencing an outage on its website and said around 7 a.m. ET that a fix had been implemented.

• The service added that customers "may experience increased origin load as global services return."

Context: Fastly helps websites with significant amounts of traffic distribute user flow across many smaller, distributed networks.

• When a CDN goes down, it often takes many sites with it, but it's usually not too hard to fix.