Security operations teams must balance visibility, storage efficiency, and investigative speed when selecting long-term monitoring data sources. NetFlow is specifically designed to meet these requirements by providing summarized metadata about network traffic rather than capturing full packet contents.

NetFlow records information such as source and destination IP addresses, ports, protocols, byte counts, and timestamps. This allows analysts to quickly identify communication patterns, unusual data transfers, and the scope of an incident without storing large volumes of raw packet data. Because NetFlow stores metadata instead of payloads, it consumes significantly less storage space, making it suitable for long-term retention over periods such as 12 months.

SPAN ports and traffic mirroring continuously copy raw network traffic, which generates massive data volumes and requires substantial storage and processing resources. These methods are effective for short-term deep packet analysis but are not practical for long-term retention. Packet capture (.pcap) files provide the most detailed visibility but consume the most storage and are typically used only for targeted, short-duration investigations.

Cybersecurity operations documentation emphasizes NetFlow as a foundational telemetry source for incident scoping, threat hunting, and anomaly detection. It enables rapid identification of compromised hosts, data exfiltration paths, and lateral movement while maintaining storage efficiency.

Therefore, NetFlow is the most appropriate source of information given the stated requirements.