Egypt returned to the Internet earlier today by reversing the "kill switch" move it made last week when it withdrew router announcements, experts said.

To restore the country's connections, Egyptian Internet service providers (ISPs) re-configured their core routers so that they once again announced their presence, letting upstream providers and other networks reestablish data pathways.

"It was pretty much similar, except reversed, to what happened last week," said Andree Toonk, the founder and lead developer of BGPmon, an open-source tool for monitoring BGP, or "border gateway protocol."

BGP is the protocol at the heart of the Internet's routing mechanism, and is used by routers to share information about the paths data traffic uses to "hop" from one network to another as it moves from a source to its destination.

The speed with which the networks reconnected was evidence that rather than physically plugging in cables, Egypt's ISPs simply began advertising their availability to other networks' routers using BGP, said Toonk.

"That, and the fact that it all happened at the same time shows the disconnect was probably not physical," said Toonk. Nor was the restoration today. "Everything was restored in about half an hour," he said.

According to Toonk's monitoring, the first BGP announcements for Egypt began at 9:30 a.m. UTC, or 11:30 a.m. local time. The start time Toonk cited was 4:30 a.m. ET and 1:30 a.m. PT in the U.S.

Internet monitoring company Renesys also pegged the reconnect time for the bulk of Egypt's networks at around 30 minutes.

Others said it took longer than that. "It wasn't quite as abrupt as last week," said Craig Labovitz, chief scientist at Arbor Networks in Chelmsford, Mass., today. "It took from a half hour to an hour."

The quick restoration of service also meant that the Egyptian government had likely ordered the digital blockage lifted, said Toonk, just as it forced ISPs to go offline last week.

Some ISPs and sites remained accessible outside Egypt during the five-day outage, said both Toonk and Labovitz, who were wary of assigning a reason for their survival when most of the country went dark. "There were a few percent of Egypt's ISPs, maybe four to five percent, that were left online," said Toonk. "Why they remained online, I don't know."