CV0-004 Troubleshooting Practice Question
A cloud administrator is troubleshooting a network connectivity issue between two VPCs connected via a VPC peering connection. The administrator has verified that the route tables are correct and that the security groups allow traffic. However, instances in VPC A cannot ping instances in VPC B. Which TWO of the following could be causing the issue? (Choose TWO.)
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
✓
Network ACLs in VPC B are blocking inbound ICMP
Network ACLs are stateless and must allow both inbound and outbound traffic; if they block inbound ICMP, ping fails, making A correct. Host-based firewall rules within the OS of the target instance can also block ICMP, making C correct. B is wrong because security groups in VPC A control inbound traffic to instances in VPC A, not to instances in VPC B. D is wrong because VPC peering supports ICMP. E is wrong because the administrator verified route tables are correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Network ACLs in VPC B are blocking inbound ICMP
Why this is correct
Network ACLs are stateless; they must explicitly allow both inbound and outbound ICMP.
- ✗
Security groups in VPC A are blocking inbound ICMP
Why it's wrong here
Security groups are stateful; if outbound is allowed, return traffic is automatically allowed.
- ✓
Host-based firewall on the target instance is blocking ping
Why this is correct
The OS firewall (e.g., iptables) can block ICMP despite cloud-level rules.
- ✗
VPC peering connection does not support ICMP
Why it's wrong here
VPC peering supports all protocols, including ICMP.
- ✗
Route tables are misconfigured
Why it's wrong here
Route tables have been verified as correct.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 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 CV0-004 exam.