The website went down for around an hour yesterday evening, but was restored just before midnight.
Twitter and other social networks were awash with rumours that the corporation had been the victim of a denial-of-service attack. However, one user known as Nevali, who describes himself as a "metadata magician at the BBC" said this wasn't the case.
"It's not a DoS [Denial of Service] attack. Routing went away. Software config or hardware problem," he tweeted.
Steve Hermann, editor of the BBC news website, apologised for the outage in a blog.
"It's not often we get a message from the BBC's technical support teams saying, 'Total outage of all BBC websites'. But for getting on for an hour this evening, until just before midnight, that's what happened," he said.
"We haven't yet had a full technical debrief, but it's clear it was a major network problem. We'd like to apologise to everyone who couldn't get on to the BBC News website during that time."