In the context of US Federal Agencies, incidents are categorized based on their impact on operations, assets, or individuals. A DoS attack that prevents or impairs the authorized functionality of networks and is still ongoing without successful mitigation efforts typically falls under Category 2 (CAT 2). This category is designated for incidents that have a significant impact, requiring immediate reporting and response. The reporting timeframe of within 2 hours as mentioned aligns with the urgency associated with CAT 2 incidents, emphasizing the need for swift action to address the attack and restore normal operations.