The federal health insurance Web site is back in business, after an outage at a Verizon data center caused it to go offline for much of the day Sunday, federal health officials said Monday.

The issue was caused by a “networking problem” at Verizon, said Julie Bataille, a spokeswoman for the Centers for Medicare and Medicaid Services, the federal agency in charge of the Web site. The site, which went down in the early morning hours on Sunday, was by in operation by 7 a.m. eastern time Monday, she said.

The problem not only affected the federal site,, but state exchange Web sites as well. It temporarily knocked out the “data hub” – the complex network built by the federal government that connects state, federal and insurance company Web sites, acting as a pipeline for the sites to verify people’s identity and eligibility for government programs.

This was the latest in a string of glitches that have marred the rollout of the health insurance Web sites, which are a critical piece of the president’s health-care law. They are supposed to give people an easy way to browse health plans, apply for government subsidies and for Medicaid, and to enroll in coverage. Starting next year, most Americans will have to carry health insurance or face a fine.

But it is more along the lines of the glitches people expected in the wake of the Oct. 1 rollout, which was plagued by more serious technical problems that the Obama administration says will not be fixed until the end of November.

“This kind of stuff is going to happen,” Kevin Counihan, chief executive of the Connecticut health exchange, said of the Sunday outage. “It’s just very typical in something this new and complex. Is it inconvenient? Sure. But is it to be expected? Absolutely.”

Also Monday, as part of a new effort to release more information about the fixes underway, federal health officials said they repaired two problems with The filter and display of insurance plans was taking minutes, they said, but now it takes seconds. And people are no longer encountering blank screens when they try to see if they are eligible for subsidies.

Both issues were on a “punch list” the administration has said it is compiling to keep track of problems and when they are fixed.

Aaron Blake contributed to this post.