Initial reports indicate the failure is hitting companies across the U.S., but few details are immediately available.

"We are currently experiencing DNS issues which could affect DMS (Digital Media Solutions) clients who also host their DNS with ATT," the carrier said in a short message posted to a service status on its Managed Services website. "Our Network Operations team is aware of the problem and is working the issue."

"Our highest level of technical support personnel have been engaged and are working to mitigate the issue," AT&T said.

The status message said there is "no estimated time" for restoring the service.