- A
R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit host 192.168.1.100 R1(config-std-nacl)# deny any R1(config-std-nacl)# exit R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2
This is correct because it creates a standard named ACL 'SSH_ACL' that permits only the management station, applies it to the VTY lines with 'ip access-class in' to filter incoming SSH connections, restricts transport to SSH only, and sets SSH version 2 globally.
- B
R1(config)# access-list SSH_ACL permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# access-group SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2
Why wrong: This is incorrect because 'access-group' is used for applying ACLs to interfaces, not to VTY lines. The correct command for VTY lines is 'ip access-class'.
- C
R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL out R1(config-line)# transport input ssh R1(config)# ip ssh version 2
Why wrong: This is incorrect because the ACL is applied with 'out' instead of 'in'. For VTY lines, 'ip access-class in' filters incoming connections; 'out' would filter outgoing connections, which is not the requirement.
- D
R1(config)# access-list SSH_ACL permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input all R1(config)# ip ssh version 2
Why wrong: This is incorrect because 'transport input all' allows both Telnet and SSH, but the requirement is to restrict to SSH only. The correct command is 'transport input ssh'.
Quick Answer
The answer is to configure a standard named ACL called SSH_ACL that permits only host 192.168.1.100, then apply it to the VTY lines with the ip access-class command in the inbound direction, while also setting transport input ssh and ip ssh version 2. This configuration is correct because the access-class command binds the ACL directly to the VTY lines, filtering all incoming TCP sessions—including SSH—before they reach the login prompt; the permit host statement allows only the management station, while the implicit deny any blocks all other sources. On the CCNA 200-301 v2 exam, this task tests your understanding of how to combine SSH access restriction with VTY ACL configuration, a common security scenario where many candidates mistakenly apply the ACL to an interface instead of the line, or forget to disable Telnet by specifying transport input ssh. A key memory tip is “ACL on the line, not the interface”—the ip access-class command is the only way to filter VTY access, and always pair it with transport input ssh to enforce encrypted management.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. 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.
You are connected to R1 via console. R1 is a router that should restrict SSH access to only the management station at 192.168.1.100. Currently, SSH is enabled but any IP can connect. Configure a standard named ACL called 'SSH_ACL' to permit only the management station, and apply it to the VTY lines to filter incoming SSH connections. Ensure the VTY lines use SSH only (no Telnet). The SSH version should be set to 2.
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
R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit host 192.168.1.100 R1(config-std-nacl)# deny any R1(config-std-nacl)# exit R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2
The standard ACL restricts inbound connections to the VTY lines. Applying it with 'ip access-class in' filters incoming Telnet/SSH sessions. Setting 'transport input ssh' disables Telnet, and 'ip ssh version 2' ensures secure SSH version 2.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit host 192.168.1.100 R1(config-std-nacl)# deny any R1(config-std-nacl)# exit R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2
Why this is correct
This is correct because it creates a standard named ACL 'SSH_ACL' that permits only the management station, applies it to the VTY lines with 'ip access-class in' to filter incoming SSH connections, restricts transport to SSH only, and sets SSH version 2 globally.
Related concept
Standard ACLs match source addresses.
- ✗
R1(config)# access-list SSH_ACL permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# access-group SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2
Why it's wrong here
This is incorrect because 'access-group' is used for applying ACLs to interfaces, not to VTY lines. The correct command for VTY lines is 'ip access-class'.
- ✗
R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL out R1(config-line)# transport input ssh R1(config)# ip ssh version 2
Why it's wrong here
This is incorrect because the ACL is applied with 'out' instead of 'in'. For VTY lines, 'ip access-class in' filters incoming connections; 'out' would filter outgoing connections, which is not the requirement.
- ✗
R1(config)# access-list SSH_ACL permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input all R1(config)# ip ssh version 2
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.
✓R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit host 192.168.1.100 R1(config-std-nacl)# deny any R1(config-std-nacl)# exit R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2Correct answer▾
Why this is correct
This is correct because it creates a standard named ACL 'SSH_ACL' that permits only the management station, applies it to the VTY lines with 'ip access-class in' to filter incoming SSH connections, restricts transport to SSH only, and sets SSH version 2 globally.
✗R1(config)# access-list SSH_ACL permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# access-group SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2Wrong answer — click to see why▾
Why this is wrong here
The command 'access-group' is used on interfaces to filter traffic, not on VTY lines. VTY lines use 'ip access-class' to filter incoming Telnet/SSH sessions.
Why candidates choose this
Candidates often confuse 'access-group' (for interfaces) with 'access-class' (for VTY lines) because both involve ACLs.
✗R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL out R1(config-line)# transport input ssh R1(config)# ip ssh version 2Wrong answer — click to see why▾
Why this is wrong here
The direction 'out' on VTY lines filters traffic originating from the router (outgoing), not incoming SSH connections. The correct direction is 'in'.
Why candidates choose this
Candidates may think 'out' is correct because they associate 'out' with traffic going out to the network, but for VTY lines, 'in' refers to connections coming into the router.
✗R1(config)# access-list SSH_ACL permit 192.168.1.100 R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input all R1(config)# ip ssh version 2Wrong answer — click to see why▾
Why this is wrong here
The command 'transport input all' permits all protocols, including Telnet, which is insecure. The requirement specifies SSH only, so 'transport input ssh' is needed.
Why candidates choose this
Candidates might use 'all' to ensure SSH works, but they overlook the security requirement to disable Telnet.
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: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Trap categories for this question
Command / output trap
This is incorrect because 'access-group' is used for applying ACLs to interfaces, not to VTY lines. The correct command for VTY lines is 'ip access-class'.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 200-301 ACL questions on filtering logic and placement.
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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 — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: R1(config)# ip access-list standard SSH_ACL R1(config-std-nacl)# permit host 192.168.1.100 R1(config-std-nacl)# deny any R1(config-std-nacl)# exit R1(config)# line vty 0 4 R1(config-line)# ip access-class SSH_ACL in R1(config-line)# transport input ssh R1(config)# ip ssh version 2 — The standard ACL restricts inbound connections to the VTY lines. Applying it with 'ip access-class in' filters incoming Telnet/SSH sessions. Setting 'transport input ssh' disables Telnet, and 'ip ssh version 2' ensures secure SSH version 2.
What should I do if I get this 200-301 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 200-301 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
About these practice questions
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Same concept, more angles
1 more ways this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network technician is troubleshooting a router that cannot be accessed via SSH. The router responds to Telnet but SSH attempts return 'connection refused'. The technician confirmed that 'ip ssh version 2' is configured and 'show ip ssh' indicates SSH is enabled. The output of 'show line vty 0 4' shows 'transport input telnet'. What should the technician do next?
hard- A.Generate a new RSA key pair and restart the SSH service.
- ✓ B.Add the 'transport input ssh' command to the VTY lines.
- C.Configure 'ip ssh version 1' to enable backward compatibility.
- D.Configure AAA authentication on the VTY lines.
Why B: The VTY lines are configured with 'transport input telnet', which explicitly allows only Telnet sessions. SSH is enabled globally, but because it is not listed in the VTY transport input, the router rejects SSH connection attempts. Adding 'transport input ssh' (or 'transport input all') under the VTY lines permits SSH connections without disrupting Telnet, solving the mismatch at the application layer.
Last reviewed: Jun 7, 2026
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