Iran’s claim that its domestic Internet system suffered a slowdown from a heavy cyberattack is possible, experts say. But knowing for sure would require a lot more details. Iran moved the country last month onto a domestic Internet, claiming a need for better cybersecurity. Experts say it’s hard to determine whether the attack was real, but it’s possible. Iran is not the only country that has built a domestic Web to filter content from the public Web. China has the most extensive and has not reported nationwide problems from cyberattacks.”]