Quick Answer
The answer is to apply a standard ACL to the vty lines using the access-class command. This is correct because standard ACLs filter traffic based solely on the source IP address, and when applied inbound to the virtual terminal lines, they restrict which management hosts can initiate SSH sessions to the router. For the ENCOR 350-401 exam, this question tests your understanding of management plane security and the distinction between interface ACLs and vty access-class restrictions. A common trap is confusing the access-group command (used on physical interfaces) with access-class (used on vty lines); remember that SSH traffic terminates on the router itself, so the filter must be applied to the line, not an interface. A helpful memory tip: "Class controls the line, Group controls the interface."
This 350-401 practice question tests your understanding of infrastructure. 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. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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 network administrator needs to allow SSH access to a router from the management network 192.168.1.0/24. Which configuration should be applied?
Apply an extended ACL to the vty lines.
Why wrong: Extended ACLs are not necessary for source-only filtering.
Apply a named ACL to the interface.
Why wrong: ACL should be applied to vty lines, not interface.
Apply an ACL to the console line.
Why wrong: Console line does not require ACL for SSH.
Apply a standard ACL to the vty lines.
Standard ACL can filter by source IP.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Apply a standard ACL to the vty lines.
Option D is correct because a standard ACL applied to the vty lines is the proper method to restrict SSH access to a router from a specific source network. Standard ACLs filter based on source IP address, and when applied to the vty lines with the 'access-class' command, they control which management hosts can initiate inbound SSH sessions to the router.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Apply an extended ACL to the vty lines.
Why it's wrong here
Extended ACLs are not necessary for source-only filtering.
Apply a named ACL to the interface.
Why it's wrong here
ACL should be applied to vty lines, not interface.
Apply an ACL to the console line.
Apply a standard ACL to the vty lines.
Why this is correct
Standard ACL can filter by source IP.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Cisco often tests the distinction between filtering traffic destined to the router (vty access-class) versus traffic passing through the router (interface ACL), leading candidates to incorrectly apply an ACL to an interface instead of the vty lines.
Detailed technical explanation
When a standard ACL is applied to vty lines using 'access-class <acl-number> in', the router evaluates the source IP of incoming Telnet/SSH packets against the ACL before allowing the session. This is distinct from interface ACLs, which filter transit traffic. In real-world deployments, this method is often combined with 'transport input ssh' on the vty lines to enforce both source-based restriction and protocol security.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
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FAQ
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Apply a standard ACL to the vty lines. — Option D is correct because a standard ACL applied to the vty lines is the proper method to restrict SSH access to a router from a specific source network. Standard ACLs filter based on source IP address, and when applied to the vty lines with the 'access-class' command, they control which management hosts can initiate inbound SSH sessions to the router.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.
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