SSCP Network and Communications Security Practice Question
A network administrator wants to block all inbound traffic except for web and email services. Which firewall rule configuration would achieve this?
⚠ Common exam trap
SSCP often tests the concept of default-deny versus default-allow, and candidates may incorrectly believe that stateful inspection alone provides sufficient security without a default policy.
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
✓
Default-deny with allow rules for HTTP, HTTPS, and SMTP
A default-deny with allow rules for HTTP, HTTPS, and SMTP is the correct approach because it blocks all inbound traffic except the specified services. This follows the principle of least privilege and ensures only necessary traffic is permitted.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Default-deny with allow rules for HTTP, HTTPS, and SMTP
Why this is correct
Default-deny drops all inbound packets unless a rule explicitly permits them, so only HTTP, HTTPS and SMTP traffic reaches the internal network. This satisfies the requirement to block everything else, since any protocol without a matching allow rule is discarded at the perimeter.
- ✗
Stateful inspection without default policy
Why it's wrong here
Stateful inspection without a default policy leaves unmatched inbound traffic to whatever the implicit rule dictates, which may permit rather than block it. It is tempting because stateful inspection tracks sessions accurately, and it would be correct once paired with an explicit default-deny rule for all other inbound traffic.
- ✗
Stateless packet filtering with a rule per service
Why it's wrong here
Stateless filtering evaluates each packet in isolation, so return traffic for permitted inbound sessions is dropped unless matching rules are written for every ephemeral port. It is tempting because per-service rules appear to permit exactly web and email, and stateless filtering would be correct where traffic patterns are fully predictable and rules can be exhaustive.
- ✗
Default-allow with deny rules for unwanted services
Why it's wrong here
Default-allow permits every service except those explicitly denied, so any unlisted port stays open, contradicting the requirement to block all inbound traffic except web and email. It is tempting because deny rules are quick to add to an existing permissive policy, and default-allow suits trusted internal networks where only specific threats need blocking.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
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.