To say an IT project like HealthCare.gov was a large-scale, complex behemoth undertaking is an understatement, to say the least. All the myriad elements of the project must be successfully interconnected for it to function properly, which clearly did not occur.
Neglect any one of these elements and it can lead to "outright failure," says Richard Spires a consultant who formerly served as the Department of Homeland Security's chief information officer.