CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. A key principle to apply: port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2.. 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.
A switchport is configured as an access port in VLAN 10, but a user plugs in a small unmanaged switch and connects multiple devices behind it. Which security feature most directly limits that behavior at the switchport?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Port security
Port security most directly limits that behavior because it can restrict how many MAC addresses are learned on the switchport. In practical terms, if the interface is supposed to support one endpoint but suddenly begins presenting multiple MAC addresses from a downstream mini-switch, port security can detect and react to that change.
This is a classic access-layer control question. VLAN assignment alone does not limit how many devices appear behind the port.
Key principle: Port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2.
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
Why this is correct
This is correct because port security can limit MAC addresses learned on the port.
Related concept
Port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2.
✗
OSPF authentication
Why it's wrong here
This is wrong because OSPF authentication is unrelated to switchport endpoint control.
When this WOULD be correct
In a scenario where the question asks about securing OSPF routing updates in a network with multiple routers, and the focus is on preventing unauthorized routing information from being exchanged, OSPF authentication would be the correct answer. This would involve configuring authentication methods to ensure only trusted routers can participate in OSPF.
✗
NetFlow
Why it's wrong here
This is wrong because NetFlow is for traffic-flow visibility, not direct access-layer limiting.
When this WOULD be correct
If the exam question asked about monitoring traffic patterns and analyzing bandwidth usage on a switchport, NetFlow would be the correct answer. For example, a question could present a scenario where a network administrator needs to track the flow of data through a specific VLAN to identify performance issues.
✗
NTP
Why it's wrong here
This is wrong because time synchronization does not limit endpoint behavior on a port.
When this WOULD be correct
In a question focused on time synchronization issues in a network, where the exam asks about ensuring accurate time across devices in a networked environment, NTP would be the correct answer. For example, if a question asks which protocol ensures that all devices have synchronized time to prevent logging discrepancies, NTP would be appropriate.
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 securityCorrect answer▾
Why this is correct
This is correct because port security can limit MAC addresses learned on the port.
✗OSPF authenticationWrong answer — click to see why▾
Why this is wrong here
OSPF authentication is a routing protocol security feature used to authenticate OSPF neighbor messages, not to control endpoint behavior on a switchport. It has no effect on limiting the number of devices connected to a port.
★ When this WOULD be the correct answer
In a scenario where the question asks about securing OSPF routing updates in a network with multiple routers, and the focus is on preventing unauthorized routing information from being exchanged, OSPF authentication would be the correct answer. This would involve configuring authentication methods to ensure only trusted routers can participate in OSPF.
Why candidates choose this
Students might confuse authentication with general security and think it could prevent unauthorized devices, but OSPF authentication only secures routing updates, not access-layer connectivity.
✗NetFlowWrong answer — click to see why▾
Why this is wrong here
NetFlow is a traffic monitoring and analysis tool that provides visibility into network flows, but it does not enforce any limits on the number of MAC addresses or devices on a switchport. It is used for accounting and troubleshooting, not access control.
★ When this WOULD be the correct answer
If the exam question asked about monitoring traffic patterns and analyzing bandwidth usage on a switchport, NetFlow would be the correct answer. For example, a question could present a scenario where a network administrator needs to track the flow of data through a specific VLAN to identify performance issues.
Why candidates choose this
Because NetFlow can detect unusual traffic patterns, a student might think it could detect or limit multiple devices, but it lacks enforcement capabilities and operates at a higher layer.
✗NTPWrong answer — click to see why▾
Why this is wrong here
NTP (Network Time Protocol) is used for clock synchronization across network devices and has no mechanism to limit the number of endpoints connected to a switchport. It is unrelated to port-level security.
★ When this WOULD be the correct answer
In a question focused on time synchronization issues in a network, where the exam asks about ensuring accurate time across devices in a networked environment, NTP would be the correct answer. For example, if a question asks which protocol ensures that all devices have synchronized time to prevent logging discrepancies, NTP would be appropriate.
Why candidates choose this
Students might mistakenly think NTP can be used for logging or time-based access control, but it only provides time synchronization, not security enforcement.
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
A frequent exam trap is assuming that VLAN assignment alone restricts the number of devices behind a switchport. VLANs only segregate traffic logically and do not prevent multiple MAC addresses from appearing on a port. Another common mistake is selecting unrelated options like OSPF authentication, which secures routing protocol exchanges but does not control Layer 2 access. NetFlow and NTP are also unrelated to limiting connected devices. The key is recognizing that only port security directly limits how many MAC addresses can be learned on a port, thus controlling the number of connected devices.
Detailed technical explanation
How to think about this question
Port security is a Cisco switch feature that restricts the number of MAC addresses learned on a single switchport. It is designed to prevent unauthorized devices from connecting to the network by limiting the port to a predefined number of MAC addresses. When a port is configured as an access port in a specific VLAN, port security can enforce a limit on how many unique MAC addresses can be learned dynamically or statically on that port, effectively controlling endpoint access at Layer 2.
The decision process for port security involves setting parameters such as the maximum number of MAC addresses allowed on the port, the violation mode (protect, restrict, or shutdown), and optionally specifying static MAC addresses. When a user connects an unmanaged switch behind the port, multiple MAC addresses appear on that single port. Port security detects this as a violation if the number of MAC addresses exceeds the configured limit, triggering the configured violation action to protect the network from unauthorized or unexpected devices.
A common exam trap is confusing VLAN assignment with endpoint control. While VLANs segment traffic logically, they do not limit how many devices can connect behind a port. Features like OSPF authentication, NetFlow, or NTP are unrelated to controlling physical or MAC-level access on a switchport. Port security directly addresses this by monitoring MAC addresses, making it the correct and practical solution for limiting multiple devices behind a single access port.
KKey Concepts to Remember
Port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2.
A switchport configured as an access port in a VLAN does not inherently limit how many devices can connect behind it.
Port security violation modes determine the switch's response when the maximum allowed MAC addresses are exceeded on a port.
VLAN assignment segments traffic but does not prevent multiple MAC addresses from appearing on a single switchport.
OSPF authentication secures routing protocol exchanges and does not affect Layer 2 device access control on switchports.
NetFlow provides traffic flow visibility and does not limit or control the number of devices connected to a switchport.
NTP synchronizes time across devices and has no role in controlling switchport endpoint behavior or security.
Port security can be configured with static or dynamic MAC addresses to enforce strict access control on switchports.
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 restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2., then practise related 200-301 questions on the same topic to reinforce the concept.
Switching and Network Access — This question tests Switching and Network Access — Port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2..
What is the correct answer to this question?
The correct answer is: Port security — Port security most directly limits that behavior because it can restrict how many MAC addresses are learned on the switchport. In practical terms, if the interface is supposed to support one endpoint but suddenly begins presenting multiple MAC addresses from a downstream mini-switch, port security can detect and react to that change.
This is a classic access-layer control question. VLAN assignment alone does not limit how many devices appear behind the port.
What should I do if I get this 200-301 question wrong?
Review port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Port security restricts the number of MAC addresses learned on a switchport to control endpoint access at Layer 2.
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