Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
An administrator wants to block all Telnet access to a router’s VTY lines and allow only SSH. Which change most directly supports that goal?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Configure the VTY lines to accept SSH and not Telnet.
This is correct because it directly restricts the management protocol accepted on the router.
B
Distractor review
Enable PortFast on the VTY lines.
This is wrong because PortFast is a switching feature, not a router management-line control.
C
Distractor review
Use DHCP snooping to protect the VTY lines.
This is wrong because DHCP snooping is unrelated to router management transport protocols.
D
Distractor review
Increase the OSPF hello interval.
This is wrong because OSPF timer changes do not secure VTY access.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting options that mention unrelated features like PortFast, DHCP snooping, or OSPF timers, which do not control remote management protocols on VTY lines. Candidates might incorrectly assume that enabling PortFast or adjusting OSPF hello intervals enhances security for router access, but these settings affect switching behavior and routing protocol timing, respectively. DHCP snooping protects against rogue DHCP servers but does not restrict Telnet or SSH access. The trap is failing to recognize that only the 'transport input' command on VTY lines directly controls accepted remote access protocols, making it the sole correct choice for blocking Telnet and allowing only SSH.
Technical deep dive
How to think about this question
Virtual Terminal (VTY) lines on Cisco routers provide remote access for device management, typically via Telnet or SSH protocols. Telnet is an older protocol that sends all data, including passwords, in plaintext, making it susceptible to interception and unauthorized access. SSH (Secure Shell), by contrast, encrypts all transmitted data, providing confidentiality and integrity for remote management sessions. Cisco IOS allows administrators to configure which protocols are accepted on VTY lines using the 'transport input' command, enabling precise control over remote access methods. To block Telnet and allow only SSH, the administrator configures the VTY lines with the command 'transport input ssh'. This setting ensures that the router accepts only SSH connections on its management interfaces, effectively disabling Telnet access. This approach is more secure and direct than relying on external network devices or access control lists to filter Telnet traffic. It enforces security at the management plane level, reducing the attack surface and preventing insecure protocols from reaching the router. A common exam trap is confusing unrelated features with VTY line security. For example, enabling PortFast affects switch port behavior in Spanning Tree Protocol and does not restrict remote access protocols. Similarly, DHCP snooping protects against rogue DHCP servers but does not control VTY access. Adjusting OSPF hello intervals influences routing protocol operations but has no effect on management protocol restrictions. Understanding the specific role of each feature prevents selecting incorrect answers that do not address the core security requirement of blocking Telnet on VTY lines.
KKey Concepts to Remember
- Cisco routers allow configuration of VTY lines to specify which remote management protocols are accepted, such as SSH or Telnet.
- Configuring VTY lines to accept only SSH blocks insecure Telnet access, enhancing router management security by enforcing encrypted sessions.
- Telnet transmits data in clear text, making it vulnerable to interception, whereas SSH encrypts management traffic to protect credentials and commands.
- The 'transport input' command on VTY lines controls which protocols are permitted for remote access, directly impacting router management plane security.
- Network administrators should disable insecure protocols like Telnet on management interfaces rather than relying solely on external filtering or ACLs.
- PortFast is a Spanning Tree Protocol feature that affects switch port behavior and does not influence router VTY line access control.
- DHCP snooping protects against rogue DHCP servers and does not control or restrict router management protocol access on VTY lines.
- Changing OSPF hello intervals affects routing protocol timing and convergence but does not impact remote management access methods on routers.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
Cisco routers allow configuration of VTY lines to specify which remote management protocols are accepted, such as SSH or Telnet.
What is the correct answer to this question?
The correct answer is: Configure the VTY lines to accept SSH and not Telnet. — The most direct change is to restrict the VTY transport protocol settings so that only SSH is accepted. In practical terms, this is cleaner and more direct than trying to depend only on traffic filtering somewhere else in the network. It changes the management-plane behavior on the router itself and removes Telnet as an accepted remote access method. This is an important management-security principle: where possible, disable the insecure service rather than merely hoping that external filters always block it.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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