[MS.BEHAVIN]

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[STARLIT]

Oliver Darcy -

Major DNS host suffers DDoS attack resulting in several major sites (including Twitter) being down this morning.

It was mostly resolved at 9:20 a.m. ET, but at 12:07 p.m. ET, the issue started to crop up again, according to one of the companies at the center of the apparent cyber attack.

The issue appears to have something to do with DNS hosts — in particular, Dyn, one of the biggest DNS companies.

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.

Dyn said on Friday that it suffering a DDoS attack, or a 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.

No group has taken credit for the DDoS attack yet. The Department of Homeland Security is monitoring the attack, Politico's Eric Geller reports.