The answer is a missing outbound rule permitting HTTPS traffic. This is correct because firewalls operate on a default-deny principle, meaning all traffic is blocked unless an explicit rule allows it; when a user at 10.0.0.1 cannot reach 203.0.113.5 on port 443, the failure occurs at the outbound stage, as the firewall drops the connection before it ever leaves the internal network. On the Systems Security Certified Practitioner SSCP exam, this scenario tests your understanding of stateful inspection and rule order, often appearing as a trick where candidates mistakenly blame an inbound rule or DNS resolution. A common trap is assuming the problem lies with the destination server, but the key is recognizing that outbound HTTPS traffic requires a specific permit rule for TCP/443. Memory tip: “Outbound, outbound, don’t let it be found” — if no rule says yes, the packet gets dropped.
SSCP Network and Communications Security Practice Question
This SSCP practice question tests your understanding of network and communications security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Firewall ruleset:
Rule 1: permit tcp any host 10.0.0.1 eq 80
Rule 2: permit tcp any host 10.0.0.2 eq 443
Rule 3: deny ip any any log
Refer to the exhibit. A user at IP 10.0.0.1 reports that they cannot access a web server at 203.0.113.5 on port 443. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The firewall does not have a rule permitting outbound traffic.
Option D is correct because the user at 10.0.0.1 cannot reach 203.0.113.5:443, which indicates that outbound traffic to that destination is not permitted. Firewalls by default block all traffic unless explicitly allowed; if no rule permits outbound HTTPS (TCP/443) traffic, the connection will be dropped. The symptom (inability to access an external web server) points to a missing outbound rule, not an inbound rule issue.
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.
✗
The firewall only permits inbound traffic to specific IPs.
Why it's wrong here
This is true but not the full reason; the issue is lack of outbound rules.
✗
The firewall rule order is incorrect.
Why it's wrong here
Rule order is not the issue; there is no permit for outbound traffic at all.
✗
The firewall blocks all outbound traffic.
Why it's wrong here
The firewall does not explicitly block outbound, but it is implicitly denied due to lack of permit rules.
✓
The firewall does not have a rule permitting outbound traffic.
Why this is correct
Without an explicit permit for outbound traffic, the implicit deny blocks it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on inbound rules when a user cannot reach an external server, forgetting that outbound traffic must also be explicitly permitted by the firewall's egress policy.
Detailed technical explanation
How to think about this question
Stateful firewalls maintain a session table and evaluate outbound traffic against egress ACLs or security policies. If no permit statement exists for source 10.0.0.1 to destination 203.0.113.5 on port 443 (HTTPS), the firewall drops the SYN packet and may send an ICMP unreachable or simply drop silently. In real-world scenarios, missing outbound rules are common when new services are deployed without updating the policy, and troubleshooting often involves checking the firewall's log for denied packets using commands like 'show log' or 'show access-list'.
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 analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
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.
Network and Communications Security — This question tests Network and Communications Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The firewall does not have a rule permitting outbound traffic. — Option D is correct because the user at 10.0.0.1 cannot reach 203.0.113.5:443, which indicates that outbound traffic to that destination is not permitted. Firewalls by default block all traffic unless explicitly allowed; if no rule permits outbound HTTPS (TCP/443) traffic, the connection will be dropped. The symptom (inability to access an external web server) points to a missing outbound rule, not an inbound rule issue.
What should I do if I get this SSCP 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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