Despite its robust appearance, more than 10 percent of the internet flickers out like a candle every day, according to researchers who unveiled on Wednesday an experimental tool that probes the network's dark places.

Ethan Katz-Bassett, a computer science Ph.D. candidate from the University of Washington introduced Hubble – a network of deep cyberspace probes scattered around the internet –- at the meeting of the North American Network Operator's Group in Bellevue, Washington. For two weeks Hubble queried a sample of 1,500 internet prefixes (a small subsection of the net) every 15 minutes. In the end it found that 10 percent of those prefixes couldn't be reached from certain corners of the internet.

Sometimes certain blocks of the internet weren't reachable at all, Katz-Bassett reported, while other times only traffic coming from particular portions of the net fell into what's called a "routing black hole." When that happens, packets sent from one computer to another – whether a request for a web page, or an e-mail message – are somehow diverted to the wrong location, where they're lost forever.

Harsha V. Madhyastha, Katz-Bassett's partner in the project, said their tentative results surprised them.

"We've found a lot more reachability problems than we expected to see, with some prefixes being unreachable from several vantage points across multiple days," Madhyastha told Wired News.

The researchers hope to build a tool that will chart these black holes in real time, by monitoring the dialogue that takes place between routers about the best path for particular traffic, and by building a permanent system of remote sensors that can send pings from various spots around the internet.

"A single unresponsive ping is likely to mean there are widespread problems, Katz-Bassett said. The larger system, which Katz-Bassett plans to build over the summer, would treat an unanswered ping as a canary in a coal mine, instantly triggering multiple probes from around the net.

Routing problems can be caused by a number of factors, ranging from problems with a particular router, often a new one, to ironic problems with a technique called "multi-homing" -– which supposed to make it easier for packets to reach their destination by allowing an internet site to simultaneously have a number of different addresses and network connections.

About 75 percent of the problems are fixed within an hour, and some last multiple days, according to their research.

Madhyastha and Katz-Bassett plan to make the Hubble data searchable by other researchers.