Net security experts said the blackout occurred after both of the top-level domain name servers for Syria became unreachable, It was unclear what the cause of this outage was. There have been similar outages over the past few years, whether due to the government shutting the servers down, problems with the physical networks serving Syria, internal infrastructure failures, or attacks from rebel groups.
The connection was restored the following day, and Syria officials blamed the outage on a "fault in optical fiber cables." Net experts, though, noted that there are 4 different conduits for Internet traffic in and out of Syria, and that the Internet is designed to reroute traffic if there is a blockage. The chance for a total blackout resulting from a problem with a single conduit would be embarrassingly small.
"In the middle of the chaos and tragedy of civil war, why is anyone surprised when the Internet stops working?" (one Internet security expert) said. "Isn't it actually more shocking and noteworthy that the Internet in Syria actually functions pretty well 360 days out of the year?" .Sources - Syria Back Online After Internet Blackout, Information Week
Syria back online after latest Internet outage, c/net