The answer is to restrict SSH access so only the 10.50.50.0/24 management subnet is permitted, typically by applying a standard access control list (ACL) on the VTY lines of the router. This is correct because SSH is a secure protocol, but security also requires controlling which source networks can reach the management plane; an ACL that permits only 10.50.50.0/24 and denies all else enforces the policy at the device level. On the CCNA 200-301 v2 exam, this tests your understanding of management-plane security and the practical use of ACLs to filter inbound VTY traffic—a common trap is thinking that simply enabling SSH is sufficient, but the question explicitly demands source-based restriction. A useful memory tip is “SSH secures the tunnel, ACL secures the door”—the protocol protects the session, but the ACL decides who gets to knock.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. A key principle to apply: access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports.. 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 router allows SSH management from anywhere on the internal network. A new policy requires that only the management subnet 10.50.50.0/24 be allowed to initiate SSH to the device. Which approach best enforces 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Restrict SSH access so only the 10.50.50.0/24 management subnet is permitted
The best approach is to use an access control mechanism that limits SSH access to the approved source subnet. In practical terms, SSH is the correct secure protocol, but protocol choice alone is not enough. The device should also restrict who is allowed to reach that management service. That usually means applying an ACL or equivalent source restriction focused on the management subnet.
This is a common management-plane security pattern: use a secure protocol, then limit the set of trusted sources that are allowed to use it.
Key principle: Access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Restrict SSH access so only the 10.50.50.0/24 management subnet is permitted
Why this is correct
This is correct because the policy is specifically about limiting management access by source.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports.
✗
Replace SSH with Telnet so the traffic is easier to identify
Why it's wrong here
This is wrong because Telnet is less secure than SSH.
When this WOULD be correct
In a different scenario where the exam question asks about simplifying network traffic analysis for a legacy system that only supports Telnet, replacing SSH with Telnet could be considered correct if the focus is on identifying and monitoring traffic rather than security.
✗
Enable PortFast on all access switches
Why it's wrong here
This is wrong because PortFast is unrelated to router management access control.
When this WOULD be correct
If the question asked about optimizing switch port performance during network convergence or reducing the time for devices to connect to the network, enabling PortFast could be the correct answer, as it helps improve efficiency in such scenarios.
✗
Raise the Syslog severity threshold
Why it's wrong here
This is wrong because logging thresholds do not restrict who can initiate SSH.
When this WOULD be correct
If the question asked about improving log management and reducing the volume of log messages generated by SSH access attempts, raising the Syslog severity threshold could be the correct answer. This would be appropriate in a scenario focused on log management rather than access control.
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.
✓Restrict SSH access so only the 10.50.50.0/24 management subnet is permittedCorrect answer▾
Why this is correct
This is correct because the policy is specifically about limiting management access by source.
✗Replace SSH with Telnet so the traffic is easier to identifyWrong answer — click to see why▾
Why this is wrong here
Telnet transmits data in plaintext, including passwords, making it highly insecure. Replacing SSH with Telnet would violate security policies and expose management traffic to eavesdropping, which is contrary to the goal of restricting access securely.
★ When this WOULD be the correct answer
In a different scenario where the exam question asks about simplifying network traffic analysis for a legacy system that only supports Telnet, replacing SSH with Telnet could be considered correct if the focus is on identifying and monitoring traffic rather than security.
Why candidates choose this
Students might think that Telnet is simpler to filter because it uses a well-known port (23), but they overlook the critical security disadvantage. The question focuses on restricting access, not on ease of identification.
✗Enable PortFast on all access switchesWrong answer — click to see why▾
Why this is wrong here
PortFast is a Spanning Tree Protocol feature used on switch ports connected to end devices to speed up convergence. It has no effect on router management access or SSH filtering, and applying it would not restrict SSH initiation.
★ When this WOULD be the correct answer
If the question asked about optimizing switch port performance during network convergence or reducing the time for devices to connect to the network, enabling PortFast could be the correct answer, as it helps improve efficiency in such scenarios.
Why candidates choose this
PortFast is a common Cisco feature that students learn about, and they might confuse it with security features like port security or access lists. The name 'PortFast' might be misassociated with 'fast access control'.
✗Raise the Syslog severity thresholdWrong answer — click to see why▾
Why this is wrong here
Syslog severity thresholds control which log messages are sent to a syslog server; they do not filter incoming traffic or restrict who can initiate SSH. Changing the threshold would not prevent unauthorized SSH attempts.
★ When this WOULD be the correct answer
If the question asked about improving log management and reducing the volume of log messages generated by SSH access attempts, raising the Syslog severity threshold could be the correct answer. This would be appropriate in a scenario focused on log management rather than access control.
Why candidates choose this
Students might think that raising the severity threshold reduces logging and thus 'hides' management traffic, but this does not enforce access control. They may confuse logging with access filtering.
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 selecting an option that changes the management protocol, such as replacing SSH with Telnet, because it seems to simplify access control. However, Telnet is insecure as it transmits data in clear text, exposing credentials to interception. Another trap is choosing unrelated features like PortFast or syslog severity thresholds, which do not control access to management services. Candidates may also overlook the need to apply an ACL to restrict source IPs, mistakenly believing that enabling SSH alone enforces the policy. This misunderstanding leads to incomplete security configurations that fail the requirement to limit SSH access to the management subnet.
Detailed technical explanation
How to think about this question
Access Control Lists (ACLs) are fundamental tools in Cisco networking used to control traffic flow by filtering packets based on criteria such as source IP addresses, destination IP addresses, and protocols. In the context of router management, ACLs can be applied to restrict which hosts or subnets are allowed to initiate management sessions like SSH. SSH (Secure Shell) is the industry-standard protocol for secure remote management because it encrypts all communication, including authentication credentials, ensuring confidentiality and integrity.
To enforce a policy that only the management subnet 10.50.50.0/24 can initiate SSH connections, an ACL is created permitting SSH traffic only from that subnet and denying all other sources. This ACL is then applied to the router’s VTY (virtual terminal) lines or inbound interface to filter incoming SSH connection attempts. This approach ensures that even if SSH is enabled globally, only trusted hosts within the management subnet can establish sessions, effectively reducing the attack surface and improving security.
A common exam trap is confusing protocol choice with access control. While SSH is the correct secure protocol, simply enabling SSH does not restrict who can connect. Another trap is assuming unrelated features like PortFast or syslog severity thresholds affect access control; they do not. PortFast optimizes Spanning Tree convergence and syslog controls logging detail, neither restricts SSH access. Understanding the distinction between protocol security and access control mechanisms is critical for correctly implementing and securing device management in Cisco environments.
KKey Concepts to Remember
Access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports.
SSH is the preferred secure management protocol for Cisco devices because it encrypts all transmitted data, preventing interception and tampering.
Applying an ACL to the VTY lines or inbound interface restricts which source IP addresses can initiate SSH sessions to the router.
A management subnet like 10.50.50.0/24 is commonly designated to centralize and secure device administration traffic.
Restricting SSH access by source subnet reduces the attack surface by allowing only trusted hosts to connect to the router’s management interface.
Replacing SSH with Telnet is insecure because Telnet transmits credentials and data in clear text, exposing the device to interception.
PortFast is a Spanning Tree Protocol feature that speeds up port transition to forwarding state and does not control access to router management.
Syslog severity thresholds control logging verbosity but do not affect network access or restrict SSH session initiation.
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
Access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports.
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.
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 access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Services and Security — This question tests Network Services and Security — Access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports..
What is the correct answer to this question?
The correct answer is: Restrict SSH access so only the 10.50.50.0/24 management subnet is permitted — The best approach is to use an access control mechanism that limits SSH access to the approved source subnet. In practical terms, SSH is the correct secure protocol, but protocol choice alone is not enough. The device should also restrict who is allowed to reach that management service. That usually means applying an ACL or equivalent source restriction focused on the management subnet.
This is a common management-plane security pattern: use a secure protocol, then limit the set of trusted sources that are allowed to use it.
What should I do if I get this 200-301 question wrong?
Review access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports., 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?
Access Control Lists (ACLs) are used on Cisco routers to filter traffic based on source IP addresses, destination IP addresses, protocols, and ports.
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