hardMultiple ChoiceObjective-mapped
CISA Practice Question: Refer to the exhibit
Exhibit
Refer to the exhibit. Exhibit: Firewall rule excerpt (Cisco ASA) access-list INSIDE extended permit tcp 10.1.1.0 255.255.255.0 any eq 443 access-list INSIDE extended permit udp 10.1.1.0 255.255.255.0 host 10.2.2.10 eq 53 access-list INSIDE extended deny ip any any interface GigabitEthernet0/0 nameif INSIDE security-level 100 ip address 10.1.1.1 255.255.255.0 interface GigabitEthernet0/1 nameif OUTSIDE security-level 0 ip address 192.168.1.1 255.255.255.0 route OUTSIDE 0.0.0.0 0.0.0.0 192.168.1.254 1
Refer to the exhibit. A security analyst notices that users on the INSIDE network (10.1.1.0/24) can browse HTTPS websites but cannot resolve domain names. What is the most likely cause?
⚠ Common exam trap
Many exam-takers assume DNS resolution failure must be due to a DNS server being unreachable (Option C), but the ACL is actually restricting the destination IP of DNS queries, not the protocol itself.
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
✓
The ACL only permits DNS traffic to host 10.2.2.10, but users need to query a different DNS server
The exhibit shows an ACL that permits DNS traffic (UDP port 53) only to host 10.2.2.10. Since users can browse HTTPS (TCP/443) but cannot resolve domain names, the ACL is blocking DNS queries to any other DNS server. Option B correctly identifies that the ACL restricts DNS to a single server, and if users are configured to query a different DNS server, resolution fails.
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 ACL denies TCP traffic to port 443
Why it's wrong here
The ACL permits TCP to any destination on port 443.
- ✓
The ACL only permits DNS traffic to host 10.2.2.10, but users need to query a different DNS server
Why this is correct
The DNS request to an external server is denied because the ACL only allows UDP to 10.2.2.10.
- ✗
The DNS server at 10.2.2.10 is unreachable
Why it's wrong here
The ACL permits UDP to 10.2.2.10 port 53, so if that server is reachable, DNS should work.
- ✗
The OUTSIDE interface has no security-level configured correctly
Why it's wrong here
Security-level 0 is standard for outside interfaces.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISA practice question is part of Courseiva's free ISACA 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 CISA exam.