SY0-701 Security Architecture Practice Question
A stateless firewall sits between a DMZ subnet 10.10.10.0/24 and an internal subnet 10.10.20.0/24. Only the web server at 10.10.10.25 should be allowed to initiate TCP sessions to the app server at 10.10.20.20 on port 8443. All other DMZ-to-internal traffic must remain blocked. Which ACL entry is the best fit on the DMZ-facing interface?
⚠ Common exam trap
The trap here is that candidates often reverse the source and destination in the permit statement (as in Option C), mistakenly thinking the ACL should allow the app server to respond, rather than correctly permitting the web server to initiate the connection from the DMZ to the internal subnet.
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
✓
permit tcp host 10.10.10.25 host 10.10.20.20 eq 8443 followed by deny ip any any
It explicitly permits only the web server at 10.10.10.25 to initiate TCP sessions to the app server at 10.10.20.20 on port 8443, then denies all other traffic. Since the firewall is stateless, it cannot track session state, so the ACL must be applied on the DMZ-facing interface to control outbound-initiated traffic from the DMZ to the internal subnet. The permit statement uses the 'host' keyword for precise source and destination, followed by an explicit deny all to block any other DMZ-to-internal traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
deny tcp 10.10.10.0/24 10.10.20.0/24 eq 8443 followed by permit ip any any
Why it's wrong here
This would block the exact traffic that must be allowed, so it does not meet the business requirement. The trailing permit is also far too broad and would undermine segmentation by allowing other traffic through.
- ✓
permit tcp host 10.10.10.25 host 10.10.20.20 eq 8443 followed by deny ip any any
Why this is correct
This rule is the least-privilege match for the stated requirement. It allows only the specific source host, destination host, and destination port needed for the application flow, while the explicit deny blocks all remaining DMZ-to-internal traffic on that interface. Because the firewall is stateless, narrowing the source and destination at the entry point is the safest way to prevent unintended exposure.
- ✗
permit tcp host 10.10.20.20 host 10.10.10.25 eq 8443 followed by deny ip any any
Why it's wrong here
This reverses the traffic direction. The app server in the internal subnet is not the initiating host in the requirement, so this rule would not permit the new session from the web server into the internal network.
- ✗
permit ip 10.10.10.0/24 10.10.20.0/24 followed by deny ip any any
Why it's wrong here
This permits every protocol and every port between the two subnets, which is far broader than needed. It increases lateral movement risk and ignores the requirement to restrict access to a single host and port.
Visual reference
Go deeper
Related to this question
Learn chapter
Firewall Types and Deployment
Key term
Firewall
A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predetermined security rules to protect trusted internal networks from untrusted external networks.
Key term
ACL
An Access Control List is a set of rules that determines who or what can access specific network resources or data.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SY0-701 practice question is part of Courseiva's free CompTIA 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 SY0-701 exam.