CEH Enumeration and System Hacking Practice Question
This CEH practice question tests your understanding of enumeration and system hacking. 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 security analyst runs `snmpwalk -v2c -c public 192.168.1.1` and receives extensive output about the device's configuration. Which of the following is the MOST effective countermeasure against this enumeration?
Why wrong: While effective, it may break management functionality; the question asks for 'most effective countermeasure', but changing community strings is a standard best practice without disabling.
B
Use SNMPv3 with encryption
Why wrong: SNMPv3 provides encryption, but if community strings are weak, enumeration may still be possible; changing default strings is more direct.
C
Change the default community string and restrict SNMP access to specific IPs
Correct. Changing community strings from defaults and using ACLs prevents unauthorized enumeration.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the default community string and restrict SNMP access to specific IPs
Option C is correct because the most effective countermeasure against SNMP enumeration via a default community string is to change the default 'public' (or 'private') string to a strong, non-guessable value and restrict SNMP access to trusted management IPs using an access control list (ACL). This prevents unauthorized querying of the MIB tree while still allowing legitimate SNMP monitoring.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Disable SNMP entirely
Why it's wrong here
While effective, it may break management functionality; the question asks for 'most effective countermeasure', but changing community strings is a standard best practice without disabling.
✗
Use SNMPv3 with encryption
Why it's wrong here
SNMPv3 provides encryption, but if community strings are weak, enumeration may still be possible; changing default strings is more direct.
✓
Change the default community string and restrict SNMP access to specific IPs
Why this is correct
Correct. Changing community strings from defaults and using ACLs prevents unauthorized enumeration.
Related concept
Read the scenario before looking for a memorised answer.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose SNMPv3 with encryption (Option B) because it sounds more secure, but the question specifically targets the misconfiguration of using the default 'public' community string on SNMPv2c, which is best remedied by changing the community string and restricting access, not by upgrading the protocol version alone.
Detailed technical explanation
How to think about this question
SNMPv2c uses community strings as plaintext passwords in UDP packets; tools like snmpwalk can enumerate the entire MIB tree (e.g., 1.3.6.1.2.1) if the community string is known. Changing the default string and applying an ACL (e.g., 'snmp-server community YourString ro 10' on Cisco IOS) ensures only authorized hosts can query the agent, while SNMPv3 would require additional configuration and is not a direct fix for a misconfigured v2c community.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Enumeration and System Hacking — This question tests Enumeration and System Hacking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the default community string and restrict SNMP access to specific IPs — Option C is correct because the most effective countermeasure against SNMP enumeration via a default community string is to change the default 'public' (or 'private') string to a strong, non-guessable value and restrict SNMP access to trusted management IPs using an access control list (ACL). This prevents unauthorized querying of the MIB tree while still allowing legitimate SNMP monitoring.
What should I do if I get this CEH question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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