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SSCP Practice Question: A company's internal network uses a /24 subnet…
A company's internal network uses a /24 subnet and has a single firewall connecting to the internet. Employees report that they cannot access an external web server at 203.0.113.50. The firewall has a rule that allows outbound HTTP. What is the most likely cause?
⚠ Common exam trap
A common mix-up: candidates assume a firewall rule allowing outbound HTTP is sufficient, forgetting that NAT is required to translate private source addresses to a routable public IP for return traffic to succeed.
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
✓
NAT is not configured for outbound traffic.
The firewall rule allows outbound HTTP, but without NAT configured, the internal hosts' private IP addresses (e.g., 192.168.1.x) are used as source addresses in packets sent to the external web server. The web server at 203.0.113.50 will see these private addresses as the source and attempt to reply to them, but private addresses are not routable on the public internet, so the return traffic never reaches the internal hosts. NAT (specifically source NAT or PAT) translates the private source IP to the firewall's public IP, enabling two-way communication.
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 default gateway on the internal hosts is incorrect.
Why it's wrong here
If hosts can reach other internal resources, the gateway is likely correct.
- ✓
NAT is not configured for outbound traffic.
Why this is correct
Internal private IPs must be translated to a public IP for internet access.
- ✗
DNS resolution is failing for the server name.
Why it's wrong here
The user is accessing by IP, so DNS is not involved.
- ✗
An ACL is blocking the destination IP.
Why it's wrong here
The rule allows HTTP, so an ACL block is unlikely unless specifically configured.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SSCP exam.