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200-301 · Question #412

If a switch port receives a new frame while it is actively transmitting a previous frame, how does it process the frames?

The correct answer is C. The new frame is placed in a queue for transmission after the previous frame.. When a switch port is actively transmitting a frame and receives a new frame, the new frame is buffered and placed into an output queue. It will be transmitted only after the previous frame has completed its egress from the port.

Submitted by olafpl· Mar 5, 2026Network Fundamentals

Question

If a switch port receives a new frame while it is actively transmitting a previous frame, how does it process the frames?

Options

  • AThe new frame is delivered first, the previous frame is dropped, and a retransmission request
  • BThe previous frame is delivered, the new frame is dropped, and a retransmission request is
  • CThe new frame is placed in a queue for transmission after the previous frame.
  • DThe two frames are processed and delivered at the same time.

How the community answered

(55 responses)
  • A
    2% (1)
  • C
    93% (51)
  • D
    5% (3)

Why each option

When a switch port is actively transmitting a frame and receives a new frame, the new frame is buffered and placed into an output queue. It will be transmitted only after the previous frame has completed its egress from the port.

AThe new frame is delivered first, the previous frame is dropped, and a retransmission request

This is incorrect; switches prioritize completing ongoing transmissions and do not drop the previous frame to deliver a new one first.

BThe previous frame is delivered, the new frame is dropped, and a retransmission request is

While the previous frame is delivered, the new frame is not typically dropped unless the queue overflows; it is buffered.

CThe new frame is placed in a queue for transmission after the previous frame.Correct

Switches operate by buffering frames. If a port is currently busy transmitting a frame, any newly received frames destined for that port will be held in an output queue until the previous frame's transmission is complete.

DThe two frames are processed and delivered at the same time.

Switches are serial devices for frame transmission on a single port; they cannot process and deliver two distinct frames simultaneously on the same physical port.

Concept tested: Ethernet switch buffering and queuing

Source: https://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/10570-41.html

Topics

#Switch port operation#Frame queuing#Ethernet switching

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