Which statement about TAP and TUN devices, which are used in a Linux/KVM cloud deployment model, is true?

Question

Options

• ATUN is for handling IP packets, but TAP is for handling Ethernet frames
• BTUN is for handling Ethernet frames, but TAP is for handling IP packets
• CTUN is for tunneling IP packets, but TAP is for tapping IP packets
• DTUN is for tunneling Ethernet frames, but TAP is for tapping Ethernet frames

• A
  86% (55)
• B
  2% (1)
• C
  8% (5)
• D
  5% (3)

Explanation

Option A is correct because TUN (network TUNnel) is a Layer 3 virtual device that operates on raw IP packets, while TAP (network TAP) is a Layer 2 virtual device that operates on full Ethernet frames - including MAC headers. In KVM/cloud deployments, TAP devices are typically attached to virtual bridges so VMs can participate in Ethernet networking, while TUN devices are used for point-to-point IP tunneling (e.g., VPNs).

Option B is simply the reverse of A - it swaps the roles of TUN and TAP, making it incorrect.

Option C misdefines TAP as "tapping IP packets" - TAP works at Layer 2 (Ethernet), not Layer 3 (IP), and "tapping" is not its functional purpose in this context.

Option D is doubly wrong: TUN does not handle Ethernet frames (that's TAP's job), and "tapping Ethernet frames" is not an accurate description of what TAP does technically.

Memory tip: Think of the layers alphabetically - TAP = Two (Layer 2, Ethernet frames), TUN = Three (Layer 3, IP packets). The letter count of "TAP" (3 letters) matching Layer 3 is a false friend - flip it: TAP is Layer 2, TUN is Layer 3.

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