On Friday morning, Dyn — a company that hosts domain name systems — announced it has been the subject of a cyberattack that caused major problems for numerous websites. People reported issues with Twitter, Spotify, SoundCloud, Vox Media sites, Airbnb and numerous other sites.

Domain name systems (DNS) are essentially the GPS of the internet, taking the text URLs you type into a browser and figuring out where those websites’ data is located on the back end. So when you type mashable.com in a browser, it shows you both the real Mashable and can quickly and easily locate the nearest server that hosts the site’s data. 

The attack was resolved as of 9:20 a.m. EST, Dyn said. 

Image: screenshot/twitter

Image: screenshot/twitter

Image: screenshot/twitter

Writing on its website, Dyn said that starting at about 7 a.m. EST, the company "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."

DDoS stands for "distributed denial of service" and is a common tactic used by hackers to take down internet-connected servers. In a DDoS attack, malicious users build a network of computers that then send massive amounts of traffic to particular servers with the goal of denying the use of those servers to other users, according to Cisco.

The source of the attack Friday was not immediately clear. 

"Hackers have no rules. One of the problems we have is that they move much faster than cyber-defenders. A DDoS attack can be launched in literally seconds, or under an hour if it's coordinated by a larger group," Steven Morgan, founder of the research firm Cybersecurity Ventures, told Mashable. "Right now, we're in the phase of figuring out where did this come from." 

This cyberattack comes at a time of heightened tension, with the US claiming it will retaliate against Russia after accusing the country of orchestrating hacks of the Democratic National Committee. 

“The internet continues to rely on protocols and infrastructure designed before cyber security was an issue.  DDoS, especially with the rise of insecure IOT devices, will continue to plague our organizations," Ben Johnson, a chief security strategist for Carbon Black, told Mashable. "Sadly, what we are seeing is only the beginning in terms of large scale botnets and disproportionate damage done.”

The attack Friday mainly affected the eastern United States, Dyn said. 

Hacker News first noted the "massive Dyn DNS outage." The site said that if sites reported as down are working for some users, those users' machines have likely cached the DNS response for those sites.

Internet service firm Level 3 communications also found that the outage primarily affected the east coast of the U.S.

Image: level3 screenshot