Cyber Defense National Guard Act This bill requires the Office of the Director of National Intelligence to report to Congress regarding the feasibility of establishing a Cyber Defense National Guard. The report shall address topics including (1) the cost of creating a Cyber Defense National Guard, (2) the number of persons needed to defend critical U.S. infrastructure from a cyberattack, (3) the sources of potential members of the Cyber Defense National Guard, and (4) which federal government elements would be best equipped to train and manage the Cyber Defense National Guard.