Question 1,725 of 1,819
Network Services and SecuritymediumMultiple ChoiceObjective-mapped

CCNA Network Services and Security Practice Question

This 200-301 practice question tests your understanding of network services and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: portFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity.. 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.

An engineer wants users to get fast link-up on access ports but also wants the switch to disable a port if another switch is connected and sends BPDUs.

Which combination of features best meets that requirement?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "best"

    Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

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

PortFast and BPDU Guard

PortFast and BPDU Guard are the classic edge-port combination for this requirement. PortFast helps a user-facing interface begin forwarding quickly so a PC or phone does not wait through the normal spanning-tree transition delay. BPDU Guard adds protection by monitoring that same port for BPDUs. If a switch is accidentally or intentionally connected and starts participating in spanning tree, BPDU Guard reacts by disabling the port to protect the Layer 2 topology. In plain language, users get quick connectivity when the port is used correctly, but the network still protects itself against someone plugging in a switch where only an endpoint should exist. That is exactly what the requirement asks for.

Key principle: PortFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity.

Answer analysis

Option-by-option breakdown

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

  • PortFast and BPDU Guard

    Why this is correct

    Correct. This is correct. PortFast provides fast host connectivity, and BPDU Guard protects the port by shutting it down if BPDUs are received from a connected switch.

    Clue confirmation

    The clue word "best" in the question point toward this answer.

    Related concept

    PortFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity.

  • DHCP snooping and DAI

    Why it's wrong here

    DHCP snooping and Dynamic ARP Inspection are useful security features, but they solve different problems. They help protect address assignment and ARP behavior, not the specific combination of fast access-port startup and protection against a rogue or accidental switch connection.

    When this WOULD be correct

    If the exam question asked for features to enhance network security and prevent unauthorized DHCP servers while ensuring valid DHCP traffic, then DHCP snooping and DAI would be the correct answer, as they work together to secure the DHCP infrastructure.

  • Root Guard and VTP pruning

    Why it's wrong here

    Root Guard can help in spanning-tree design, but it is not the standard feature used to give quick edge-port startup. VTP pruning is unrelated to the core requirement. The question is specifically describing the common edge-port hardening pair, which is PortFast with BPDU Guard.

    When this WOULD be correct

    If the exam question focused on maintaining the stability of the spanning tree topology in a multi-switch environment while allowing for efficient VLAN management, then Root Guard could be the correct answer. For instance, a scenario where the goal is to prevent a switch from becoming the root bridge would make this option valid.

  • Port security and CDP

    Why it's wrong here

    Port security controls allowed MAC addresses, and CDP provides device information. Neither pair directly matches the two-part requirement as completely as PortFast and BPDU Guard do.

    When this WOULD be correct

    If the exam question asked for a method to secure access ports against unauthorized devices while also enabling monitoring of connected devices, then Port security and CDP could be the correct answer. This would focus on ensuring only known devices connect while utilizing CDP for network topology information.

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.

PortFast and BPDU GuardCorrect answer

Why this is correct

Correct. This is correct. PortFast provides fast host connectivity, and BPDU Guard protects the port by shutting it down if BPDUs are received from a connected switch.

DHCP snooping and DAIWrong answer — click to see why

Why this is wrong here

DHCP snooping and DAI (Dynamic ARP Inspection) do not address the requirement of disabling a port upon receiving BPDUs; they focus on protecting against rogue DHCP servers and ARP spoofing, respectively.

★ When this WOULD be the correct answer

If the exam question asked for features to enhance network security and prevent unauthorized DHCP servers while ensuring valid DHCP traffic, then DHCP snooping and DAI would be the correct answer, as they work together to secure the DHCP infrastructure.

Why candidates choose this

Candidates may find this option tempting because both DHCP snooping and DAI are well-known security features in networking, leading them to mistakenly associate them with port protection and network integrity.

Root Guard and VTP pruningWrong answer — click to see why

Why this is wrong here

Root Guard and VTP pruning do not address the requirement of quickly enabling access ports and disabling them upon receiving BPDUs. Root Guard is used to prevent a port from becoming a root port, while VTP pruning optimizes VLAN traffic, neither of which directly manage port states based on BPDU reception.

★ When this WOULD be the correct answer

If the exam question focused on maintaining the stability of the spanning tree topology in a multi-switch environment while allowing for efficient VLAN management, then Root Guard could be the correct answer. For instance, a scenario where the goal is to prevent a switch from becoming the root bridge would make this option valid.

Why candidates choose this

Candidates may choose this option because they recognize the importance of spanning tree protocols and may mistakenly believe that Root Guard's function of managing root bridge elections aligns with the need to control port states in response to BPDUs.

Port security and CDPWrong answer — click to see why

Why this is wrong here

Port security and CDP do not provide the necessary functionality to disable a port when BPDUs are received. Port security can limit the number of MAC addresses but does not specifically address BPDU handling.

★ When this WOULD be the correct answer

If the exam question asked for a method to secure access ports against unauthorized devices while also enabling monitoring of connected devices, then Port security and CDP could be the correct answer. This would focus on ensuring only known devices connect while utilizing CDP for network topology information.

Why candidates choose this

Candidates may choose this option because they recognize that Port security is a common feature for securing switch ports, and they might mistakenly believe that CDP's monitoring capabilities align with the requirements of the question.

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

Avoid confusing BPDU Guard with other guard features like Root Guard or Loop Guard, which serve different purposes.

Detailed technical explanation

How to think about this question

PortFast is a Cisco Catalyst switch feature that allows access ports to bypass the usual Spanning Tree Protocol (STP) listening and learning states, enabling immediate transition to the forwarding state. This is critical for endpoints like PCs or IP phones that require fast network connectivity without waiting for STP convergence, which normally takes 30 to 50 seconds. PortFast is only intended for ports connected directly to end devices, not other switches, to prevent Layer 2 loops. BPDU Guard complements PortFast by monitoring access ports for Bridge Protocol Data Units (BPDUs). If a BPDU is received on a PortFast-enabled port, BPDU Guard immediately disables the port (puts it into err-disable state) to protect the network topology from potential loops caused by unauthorized or accidental switch connections. This combination ensures fast link-up for legitimate hosts while securing the network against rogue switches. A common exam trap is confusing PortFast and BPDU Guard with other security features like Root Guard or DHCP snooping. PortFast alone speeds up connectivity but does not protect against rogue switches. BPDU Guard specifically disables ports receiving BPDUs on PortFast ports, which is the exact behavior required. Understanding this distinction is crucial for correctly answering questions about fast link-up and Layer 2 security in CCNA exams.

KKey Concepts to Remember

  • PortFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity.
  • BPDU Guard disables a PortFast-enabled port if it receives BPDUs, preventing rogue switches from causing Layer 2 loops.
  • STP normally imposes a delay on port forwarding to prevent loops, but PortFast safely bypasses this delay on edge ports.
  • BPDU Guard protects the network topology by err-disabling ports that receive unexpected BPDUs on PortFast ports.
  • PortFast should only be enabled on ports connected to end devices, never on ports connecting to other switches.
  • Root Guard protects the root bridge election process but does not provide fast link-up or port shutdown on BPDU reception.
  • DHCP snooping and Dynamic ARP Inspection protect IP address assignment and ARP spoofing but do not affect STP port states.
  • Port security limits MAC addresses on a port but does not speed up STP convergence or disable ports on BPDU reception.

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

PortFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity.

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 portFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity., 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?

Network Services and Security — This question tests Network Services and Security — PortFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity..

What is the correct answer to this question?

The correct answer is: PortFast and BPDU Guard — PortFast and BPDU Guard are the classic edge-port combination for this requirement. PortFast helps a user-facing interface begin forwarding quickly so a PC or phone does not wait through the normal spanning-tree transition delay. BPDU Guard adds protection by monitoring that same port for BPDUs. If a switch is accidentally or intentionally connected and starts participating in spanning tree, BPDU Guard reacts by disabling the port to protect the Layer 2 topology. In plain language, users get quick connectivity when the port is used correctly, but the network still protects itself against someone plugging in a switch where only an endpoint should exist. That is exactly what the requirement asks for.

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

Review portFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity., then practise related 200-301 questions on the same topic to reinforce the concept.

Are there clue words in this question I should notice?

Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

What is the key concept behind this question?

PortFast enables immediate forwarding on access ports by bypassing STP listening and learning states to speed up host connectivity.

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Last reviewed: May 17, 2026

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