A massive cyberattack caused major websites to go down across the internet A massive cyberattack caused major websites to go down across the internet

AP Photo/Connie Zhou

Internet users around the world, but mostly in the US, reported that some top websites were not loading on Friday morning.

The affected sites included Amazon, Twitter, Etsy, Github, and Spotify.

The issue appeared to have something to do with DNS hosts.

Domain Name Servers are a core part of the internet's backbone. They translate what you type into your browser —www.businessinsider.com, for example — into IP addresses that computers can understand.

And as it happens, Dyn, a major DNS host, is suffering a DDoS attack, or distributed denial of service. That basically means hackers are overwhelming Dyn's servers with useless data and repeated load requests, preventing useful data — the Twitter IP address, for example — from getting through.

At 9:20 a.m. ET, Dyn said that its systems were back to normal. 

Dyn posted on Friday morning:

Starting at 11:10 UTC on October 21th-Friday 2016 we began monitoring and mitigating a DDoS attack against our Dyn Managed DNS infrastructure. Some customers may experience increased DNS query latency and delayed zone propagation during this time. Updates will be posted as information becomes available.

It later updated its status with:

This attack is mainly impacting US East and is impacting Managed DNS customer in this region. Our Engineers are continuing to work on mitigating this issue.

Dyn updated to say services are back to normal as of 9:37 a.m. ET: 

"Services have been restored to normal as of 13:20 UTC."

CNBC reported that Amazon investigated the issue as well. "Amazon & DynDNS investigating internet outage reports on east coast of U.S. amid reports of major websites not working properly," it somehow tweeted.

Earlier this month, the United States transferred its oversight of DNS to an international non-profit group, a move that had been more than 20 years in the making. 

Here's a map of outages as of 9:20 a.m. ET, via Level3:

Level3/Down Detector

According to Hacker News and reports, some of the sites affected include:

- DYN

- Twitter

- Etsy

- Github

- Soundcloud

- Spotify

- Heroku

- Pagerduty

- Shopify

- Okta

- Zendesk

- Business Insider