In the NetFlow flow-record format, a dataflow set is a collection of data records that follow the template FlowSet in an export packet. Each data record corresponds to a flow and contains values for the fields defined in the template FlowSet. This allows for efficient organization and retrieval of flow information by NetFlow collectors.
References:
* Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS)
* NetFlow Version 9 Flow-Record Format Documentation

Defense-in-depth is a security strategy where multiple layers of defense are placed throughout an information technology (IT) system. It addresses physical, technical, and administrative controls to provide redundancy and ensure that if one layer fails, others will be in place to thwart an attack. References: Cisco Tech Roles - CyberOps Engineer