350-701 Question #198: Real Exam Question with Answer & Explanation

Question

Which two fields are defined in the NetFlow flow? (Choose two.)

Options

• Atype of service byte
• BLayer 4 protocol type
• Cclass of service bits
• Doutput logical interface
• Edestination port

Explanation

NetFlow defines a unique flow based on a 7-tuple key, which typically includes the Type of Service (ToS) byte and the destination port.

Common mistakes.

• B. While the Layer 4 protocol type is part of the 7-tuple, the specific field name 'Layer 4 protocol type' is generally covered by the protocol identifier, and ToS byte and Destination Port are more directly distinct fields in the standard 7-tuple key.
• C. Class of Service (CoS) bits are primarily used in Layer 2 (Ethernet) frames for QoS within a local segment and are not a defining characteristic of a NetFlow flow, which operates at Layer 3/4.
• D. The output logical interface, while recorded for flow statistics, is not part of the standard 7-tuple key used to define a flow itself, unlike the input interface.

Concept tested. NetFlow flow key components

Reference. https://www.cisco.com/c/en/us/products/collateral/ios-nx-os-software/ios-netflow/prod_white_paper0900aecd80406232.html

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