Question 41 of 1,819
Switching and Network AccessmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is the listening port state. In the classic 802.1D Spanning Tree Protocol, the listening state is the transitional phase where a switch port processes incoming BPDUs and actively participates in the STP election process, but it does not yet learn MAC addresses or forward user traffic. This is because the switch is still determining the port’s ultimate role—root or designated—and must wait for the forward delay timer to expire before moving to the learning state. On the CCNA 200-301 v2 exam, this concept tests your understanding of the STP port state sequence and the specific responsibilities at each stage. A common trap is confusing listening with learning: both block traffic, but only learning populates the MAC address table. A useful memory tip is to think of the states in order—blocking, listening, learning, forwarding—and remember that “listening” means the port is “listening to BPDUs” but not yet “learning addresses.”

CCNA Switching and Network Access Practice Question

This 200-301 practice question tests your understanding of switching and network access. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: the Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Which spanning-tree port state listens for BPDUs and participates in STP, but does not learn MAC addresses yet?

Question 1mediummultiple choice
Read the full NAT/PAT explanation →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Listening

In the classic 802.1D sequence, the listening state processes BPDUs and prepares for forwarding decisions, but it does not populate the MAC address table yet.

Key principle: The Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Blocking

    Why it's wrong here

    Blocking receives BPDUs but does not actively prepare to forward the way listening does in the transition sequence.

    When this WOULD be correct

    If the question asked which port state does not forward frames and only listens for BPDUs without participating in STP, then Blocking would be the correct answer. This would imply a focus on the prevention of loops rather than active participation.

  • Listening

    Why this is correct

    Correct. Listening occurs before learning and forwarding.

    Related concept

    The Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks.

  • Learning

    Why it's wrong here

    Learning populates the MAC table; that is specifically what the question excludes.

    When this WOULD be correct

    If the question asked about a state that both listens for BPDUs and learns MAC addresses, such as during the transition from Listening to Forwarding, then 'Learning' would be the correct answer.

  • Forwarding

    Why it's wrong here

    Forwarding both learns and forwards traffic.

    When this WOULD be correct

    If the question asked for the state that both listens for BPDUs and actively forwards data frames while learning MAC addresses, 'Forwarding' would be the correct answer, as it describes the port state that fully participates in STP and data transmission.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

ListeningCorrect answer

Why this is correct

Correct. Listening occurs before learning and forwarding.

BlockingWrong answer — click to see why

Why this is wrong here

In the blocking state, the port does not participate in STP actively; it only receives BPDUs but does not send them or transition toward forwarding. The question specifies a state that listens for BPDUs and participates in STP, which is the listening state, not blocking.

★ When this WOULD be the correct answer

If the question asked which port state does not forward frames and only listens for BPDUs without participating in STP, then Blocking would be the correct answer. This would imply a focus on the prevention of loops rather than active participation.

Why candidates choose this

Students often confuse blocking with listening because both states do not forward traffic and both receive BPDUs. However, blocking is the initial state after a port is enabled, and it does not actively participate in STP decision-making like listening does.

LearningWrong answer — click to see why

Why this is wrong here

The learning state populates the MAC address table by learning source MAC addresses from incoming frames, which directly contradicts the question's requirement that the state does not learn MAC addresses. Learning occurs after listening and before forwarding.

★ When this WOULD be the correct answer

If the question asked about a state that both listens for BPDUs and learns MAC addresses, such as during the transition from Listening to Forwarding, then 'Learning' would be the correct answer.

Why candidates choose this

Students may think that learning is the state where the port learns about the network topology via BPDUs, but in STP, learning specifically refers to MAC address learning, not BPDU processing. The listening state is where BPDU processing and STP participation occur without MAC learning.

ForwardingWrong answer — click to see why

Why this is wrong here

The forwarding state both learns MAC addresses and forwards traffic, which violates the condition that the state does not learn MAC addresses. Forwarding is the final state where the port is fully operational.

★ When this WOULD be the correct answer

If the question asked for the state that both listens for BPDUs and actively forwards data frames while learning MAC addresses, 'Forwarding' would be the correct answer, as it describes the port state that fully participates in STP and data transmission.

Why candidates choose this

Some students might assume that forwarding includes only traffic forwarding and not MAC learning, but in STP, the forwarding state also includes learning MAC addresses from incoming frames. The listening state is the only state that participates in STP without learning MAC addresses.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

Be careful not to confuse the listening state with learning, as both involve BPDU processing but differ in MAC address table updates.

Detailed technical explanation

How to think about this question

Spanning Tree Protocol (STP) is a Layer 2 protocol designed to prevent switching loops in Ethernet networks by selectively blocking redundant paths. STP ports transition through several states—blocking, listening, learning, and forwarding—to ensure a stable and loop-free topology. The listening state is a transitional phase where the port actively processes BPDUs to participate in STP topology decisions but does not yet learn MAC addresses or forward frames. This state allows the switch to confirm that no loops exist before allowing traffic to flow. During the listening state, the switch port listens for BPDUs from other switches to determine if it should transition to the learning state or revert to blocking. The port does not populate the MAC address table in this state, which prevents premature forwarding of frames that could cause loops. Once the port confirms that it is safe to forward traffic, it moves to the learning state, where it begins to populate the MAC address table with source addresses from received frames. This staged approach ensures network stability and loop prevention. A common exam trap is confusing the listening and learning states because both occur before forwarding. Candidates often mistakenly believe that MAC address learning starts in the listening state, but it actually begins in the learning state. Practically, this distinction prevents the switch from forwarding frames before the topology is stable, avoiding temporary loops. Understanding this behavior is essential for troubleshooting STP issues and correctly answering CCNA questions about port states.

KKey Concepts to Remember

  • The Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks.
  • The listening port state in STP processes Bridge Protocol Data Units (BPDUs) to participate in topology decisions without learning MAC addresses.
  • In the listening state, a switch port prepares to transition to the learning state by determining if it should forward frames, but it does not populate the MAC address table yet.
  • The blocking port state receives BPDUs but does not forward frames or learn MAC addresses, effectively preventing loops by blocking redundant paths.
  • The learning port state populates the MAC address table by learning source MAC addresses from frames but does not forward frames yet.
  • The forwarding port state both learns MAC addresses and forwards frames, allowing normal traffic flow in the network.
  • STP port states follow a defined sequence: blocking → listening → learning → forwarding, with each state serving a specific role in loop prevention and topology convergence.
  • Understanding the difference between listening and learning states is critical to avoid confusion about when MAC address learning begins during STP convergence.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

The Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks.

Real-world example

How this comes up in practice

A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.

What to study next

Got this wrong? Here's your next step.

Review the Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks., then practise related 200-301 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this 200-301 question test?

Switching and Network Access — This question tests Switching and Network Access — The Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks..

What is the correct answer to this question?

The correct answer is: Listening — In the classic 802.1D sequence, the listening state processes BPDUs and prepares for forwarding decisions, but it does not populate the MAC address table yet.

What should I do if I get this 200-301 question wrong?

Review the Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks., then practise related 200-301 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

The Spanning Tree Protocol (STP) uses port states to prevent Layer 2 loops and ensure a loop-free topology in switched networks.

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Same concept, more angles

1 more ways this is tested on 200-301

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. Which STP port state on a classic 802.1D switch listens for BPDUs and prepares to participate in the topology, but does not yet learn MAC addresses?

easy
  • A.Listening
  • B.Learning
  • C.Forwarding
  • D.Disabled

Why A: In classic STP, the listening state processes BPDUs and waits before learning begins. The learning state is when the switch starts populating the MAC table.

Last reviewed: May 17, 2026

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