- A
Port Security: Limits the number of MAC addresses allowed on a switch port to prevent MAC flooding attacks.
Port Security restricts the number of MAC addresses learned on a port, preventing MAC address table overflow attacks (MAC flooding).
- B
Port Security: Prevents unauthorized users from connecting to the network by blocking all traffic from unknown MAC addresses.
Why wrong: This is incorrect because Port Security does not block all traffic from unknown MAC addresses by default; it can be configured to drop, shut down, or restrict the port when a violation occurs.
- C
Port Security: Prevents DHCP starvation attacks by limiting the number of DHCP requests per second.
Why wrong: This is incorrect because DHCP starvation attacks are mitigated by DHCP snooping, not Port Security. Port Security limits MAC addresses, not DHCP requests.
- D
Port Security: Prevents ARP spoofing attacks by validating ARP packets on a port.
Why wrong: This is incorrect because ARP spoofing is prevented by Dynamic ARP Inspection (DAI), not Port Security. Port Security deals with MAC addresses, not ARP validation.
Quick Answer
The answer is port security, which limits the number of MAC addresses allowed on a switch port to prevent MAC flooding attacks. This works by configuring a maximum MAC address count per interface; once that limit is reached, the switch drops any traffic from unknown source MACs, effectively starving an attacker’s attempt to overflow the CAM table. On the CCNA 200-301 v2 exam, this concept often appears in matching or scenario-based questions where you must distinguish port security from features like DHCP snooping or DAI—a common trap is confusing MAC address restriction with ARP validation. A reliable memory tip is to think of port security as a “bouncer” at the switch port door: it checks the ID (MAC) of every device and refuses entry once the guest list is full.
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: port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access.. 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.
Match each switch security or protection feature to its most accurate purpose.
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
Port Security: Limits the number of MAC addresses allowed on a switch port to prevent MAC flooding attacks.
Each security feature protects against specific threats: port security limits MAC addresses, DHCP snooping blocks rogue DHCP servers, DAI validates ARP, storm control limits traffic storms, root guard enforces STP root placement, and BPDU guard protects against rogue BPDUs on access ports.
Key principle: Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Port Security: Limits the number of MAC addresses allowed on a switch port to prevent MAC flooding attacks.
Why this is correct
Port Security restricts the number of MAC addresses learned on a port, preventing MAC address table overflow attacks (MAC flooding).
Related concept
Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access.
- ✗
Port Security: Prevents unauthorized users from connecting to the network by blocking all traffic from unknown MAC addresses.
Why it's wrong here
This is incorrect because Port Security does not block all traffic from unknown MAC addresses by default; it can be configured to drop, shut down, or restrict the port when a violation occurs.
- ✗
Port Security: Prevents DHCP starvation attacks by limiting the number of DHCP requests per second.
Why it's wrong here
This is incorrect because DHCP starvation attacks are mitigated by DHCP snooping, not Port Security. Port Security limits MAC addresses, not DHCP requests.
- ✗
Port Security: Prevents ARP spoofing attacks by validating ARP packets on a port.
Why it's wrong here
This is incorrect because ARP spoofing is prevented by Dynamic ARP Inspection (DAI), not Port Security. Port Security deals with MAC addresses, not ARP validation.
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.
✓Port Security: Limits the number of MAC addresses allowed on a switch port to prevent MAC flooding attacks.Correct answer▾
Why this is correct
Port Security restricts the number of MAC addresses learned on a port, preventing MAC address table overflow attacks (MAC flooding).
✗Port Security: Prevents unauthorized users from connecting to the network by blocking all traffic from unknown MAC addresses.Wrong answer — click to see why▾
Why this is wrong here
Port Security does not block all unknown MAC traffic; it takes action only when the maximum MAC limit is exceeded or a sticky MAC is violated.
Why candidates choose this
Candidates may think Port Security blocks unknown MACs outright, but it actually allows unknown MACs until the limit is reached.
✗Port Security: Prevents DHCP starvation attacks by limiting the number of DHCP requests per second.Wrong answer — click to see why▾
Why this is wrong here
Port Security does not inspect DHCP packets; DHCP snooping is the feature that limits DHCP request rates.
Why candidates choose this
Candidates may confuse Port Security with DHCP snooping because both involve limiting some aspect of network traffic.
✗Port Security: Prevents ARP spoofing attacks by validating ARP packets on a port.Wrong answer — click to see why▾
Why this is wrong here
Port Security does not inspect ARP packets; DAI uses DHCP snooping bindings to validate ARP messages.
Why candidates choose this
Candidates may associate port-level security with ARP protection, but DAI is the specific feature for ARP spoofing.
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
Do not confuse Port Security with other security features. Port Security limits MAC addresses; it does not inspect DHCP, ARP, or BPDU packets. Each feature has a distinct purpose.
Detailed technical explanation
How to think about this question
Switch security features are critical components in protecting Layer 2 networks from common attacks and misconfigurations. Port Security limits the number of MAC addresses on a switch port, preventing unauthorized devices from connecting or MAC flooding attacks that can disrupt the MAC address table. BPDU Guard protects the Spanning Tree Protocol topology by disabling ports that receive unexpected BPDUs, which are typically only expected on switch-to-switch links, not on edge ports connected to end devices. DHCP Snooping monitors DHCP traffic to build a trusted database of IP-to-MAC bindings and blocks DHCP offers from rogue servers, preventing IP address conflicts and unauthorized network access. Dynamic ARP Inspection uses this trusted binding table to validate ARP packets, ensuring that devices cannot spoof IP-to-MAC mappings and launch man-in-the-middle attacks. These features complement each other by securing different aspects of Layer 2 communication and IP address management. A common exam trap is confusing the purposes of these features because they all enhance switch security but operate differently. For example, BPDU Guard does not limit MAC addresses but protects STP topology, while Port Security limits MAC addresses but does not inspect DHCP or ARP traffic. Understanding the distinct role of each feature helps avoid mistakes in design and troubleshooting scenarios. In practical networks, these features are often deployed together to provide layered security against various threats at the access layer.
KKey Concepts to Remember
- Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access.
- BPDU Guard disables a switch port immediately if it receives Bridge Protocol Data Units (BPDUs) on a port configured as an edge port, protecting against potential spanning-tree topology loops.
- DHCP Snooping builds a trusted binding table by monitoring DHCP messages and blocks DHCP responses from untrusted sources to prevent rogue DHCP servers from assigning incorrect IP addresses.
- Dynamic ARP Inspection (DAI) validates ARP packets against the DHCP Snooping binding table to prevent ARP spoofing and man-in-the-middle attacks on a switched network.
- Switch security features like Port Security, BPDU Guard, DHCP Snooping, and Dynamic ARP Inspection each protect different layers and attack vectors in the LAN environment.
- Port Security enforces MAC address limits per port, which helps prevent MAC flooding attacks that can compromise VLAN segmentation and switch forwarding tables.
- BPDU Guard is essential for protecting the Spanning Tree Protocol (STP) topology by disabling ports that should not receive BPDUs, thus preventing accidental or malicious topology changes.
- DHCP Snooping and Dynamic ARP Inspection work together to secure IP address assignment and ARP resolution, ensuring only trusted devices participate in network communication.
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
Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access.
Real-world example
How this comes up in practice
A practitioner preparing for the 200-301 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Review port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access., 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 — Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access..
What is the correct answer to this question?
The correct answer is: Port Security: Limits the number of MAC addresses allowed on a switch port to prevent MAC flooding attacks. — Each security feature protects against specific threats: port security limits MAC addresses, DHCP snooping blocks rogue DHCP servers, DAI validates ARP, storm control limits traffic storms, root guard enforces STP root placement, and BPDU guard protects against rogue BPDUs on access ports.
What should I do if I get this 200-301 question wrong?
Review port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Port security on a Cisco switch restricts the number and identity of MAC addresses allowed on a specific switch port to prevent unauthorized device access.
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Last reviewed: May 17, 2026
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