This LFCS practice question tests your understanding of networking. 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. 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 systems administrator is responsible for a production Linux server running CentOS 7 that provides SSH access to users. The administrator decides to tighten security by restricting SSH access to a specific management subnet 10.0.0.0/24. While connected to the server via SSH from a workstation on 10.0.0.50, the administrator adds the following iptables rule: iptables -A INPUT -p tcp --dport 22 -s 10.0.0.0/24 -j ACCEPT followed by iptables -P INPUT DROP. Immediately after the rule change, the administrator loses all connectivity to the server, including SSH. The administrator suspects that the new default policy dropped the existing SSH session. What is the most reliable method for the administrator to regain access to the server without rebooting?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "immediately / without restart"
Why it matters: Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use IPMI or iDRAC to access the server's console and remove or modify the iptables rules.
Option C is correct because IPMI (Intelligent Platform Management Interface) or iDRAC (Integrated Dell Remote Access Controller) provides out-of-band management access to the server's console, independent of the operating system's network stack. This allows the administrator to log in locally, remove or modify the iptables rules that dropped the SSH session, and restore connectivity without rebooting. Since the default INPUT policy was set to DROP, all new and existing SSH packets are blocked, but out-of-band management bypasses iptables entirely.
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.
✗
Use netcat to send a TCP reset packet to the SSH server.
Why it's wrong here
Not feasible without connectivity; netcat cannot restore a blocked session.
✗
Use iptables-save and iptables-restore from another host on the same subnet.
Why it's wrong here
Other hosts cannot connect to the server because the INPUT chain drops all traffic.
✓
Use IPMI or iDRAC to access the server's console and remove or modify the iptables rules.
Why this is correct
Out-of-band management provides console access independent of network.
Clue confirmation
The clue word "immediately / without restart" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Boot the server into single-user mode and flush iptables rules.
Why it's wrong here
Requires physical access and disrupts production; networking may not be available.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume iptables rules only affect new connections, forgetting that changing the default policy to DROP without a stateful rule for ESTABLISHED connections will immediately terminate existing sessions, and they overlook out-of-band management as the only non-reboot recovery option.
Detailed technical explanation
How to think about this question
When iptables -P INPUT DROP is set, the default policy drops all packets that do not match an explicit ACCEPT rule, including packets belonging to established SSH sessions because the connection tracking state (e.g., ESTABLISHED) is not matched unless a rule like -m state --state ESTABLISHED,RELATED -j ACCEPT is present. Out-of-band management interfaces like IPMI (using IPMI over LAN or serial console) operate on a separate management controller (BMC) with its own network stack and are unaffected by host-based firewall rules, making them the only reliable recovery method without a reboot.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking — This question tests Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use IPMI or iDRAC to access the server's console and remove or modify the iptables rules. — Option C is correct because IPMI (Intelligent Platform Management Interface) or iDRAC (Integrated Dell Remote Access Controller) provides out-of-band management access to the server's console, independent of the operating system's network stack. This allows the administrator to log in locally, remove or modify the iptables rules that dropped the SSH session, and restore connectivity without rebooting. Since the default INPUT policy was set to DROP, all new and existing SSH packets are blocked, but out-of-band management bypasses iptables entirely.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "immediately / without restart". Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
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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