Internet service in North Korea went out for a second straight day  Tuesday, this time for about 30 minutes before the Web was restored, according to Dyn Research, a company that reports on Internet performance. The spotty service started four days after U.S. President Barack Obama said he would weigh a “proportional response” to the Sony hack the U.S. blamed on North Korea and led to Sony Pictures initially canceling the Christmas Day premiere of “The Interview.” The U.S. has not claimed responsibility for the disruption of North Korea’s Internet service.

While the outages left an entire country cut off from the Internet, only a few North Koreans are impacted by the disruption. There are only 1,024 IP addresses in North Korea, compared to 1.5 billion in the U.S., making North Korea’s Web-connected population among the smallest in the world, CNN Money reported.

Only “high level officials,” nongovernmental organizations and embassy workers are granted Internet access in the isolated country, said Joo Seong Ha, a North Korean journalist who defected to the South, the Diplomat reported. North Korean universities also have the Internet, but the Communist government tracks their Web activity. The few ordinary North Korean citizens who are on the Web have access to the country’s intranet, which includes “censored news,” “official documents” and a “rudimentary email service,” according to a 2011 profile in the Atlantic. They mostly access the intranet via Chinese-made computers, and Chinese servers host most of the country's Internet traffic, the New York Times reported. North Korea's only computer manufacturer, Morning Panda, produced only about 10,000 units in 2011.     

North Korea Monday suffered a nearly 10-hour Internet outage before service was restored.

The disruption of service may mean North Korea’s Internet is under attack, but the outage can also be explained by power issues, Dyn Research said. Pyongyang also may be intentionally shutting off its Internet so it can’t be attacked. Dyn noted Internet outages in North Korea are not unusual.

“A long pattern of up-and-down connectivity, followed by a total outage, seems consistent with a fragile network under external attack. But it’s also consistent with more common causes, such as power problems. Point causes such as breaks in fiber optic cables, or deliberate upstream provider disconnections, seem less likely because they don’t generate prolonged instability before a total failure,” the company said in a blog post Tuesday. “We can only guess. The data themselves don’t speak to motivations, or distinguish human factors from physical infrastructure problems.”