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TroubleshootinghardMultiple ChoiceObjective-mapped

CV0-004 Troubleshooting Practice Question

Network Topology
$ aws ec2 describe-instancesregion us-east-1instance-ids i-0abcd1234efgh5678Refer to the exhibit.```"Reservations": ["Groups": [],"Instances": ["InstanceId": "i-0abcd1234efgh5678","ImageId": "ami-0abcdef1234567890","State": {"Code": 16,"Name": "running"},"PrivateIpAddress": "10.0.1.50","SecurityGroups": ["GroupName": "web-sg","GroupId": "sg-0a1b2c3d4e5f67890"],"SubnetId": "subnet-0a1b2c3d4e5f67890","VpcId": "vpc-0a1b2c3d4e5f67890","Tags": ["Key": "Name","Value": "web-server-01"

A cloud administrator is troubleshooting why web-server-01 is not receiving traffic from an internet-facing load balancer. The load balancer is in the same VPC and subnet. According to the exhibit, what is the most likely reason?

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 security group attached to the instance does not allow traffic from the load balancer

The exhibit likely shows the instance's security group 'web-sg' but no inbound rule allowing HTTP traffic from the load balancer. Since the load balancer is internet-facing and in the same VPC, it can route traffic to the instance via private IP. However, the instance's security group must explicitly allow inbound traffic from the load balancer (or its security group). Without that rule, traffic is blocked. Therefore, the most likely reason is the security group not allowing traffic from the load balancer, making option A 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.

  • The security group attached to the instance does not allow traffic from the load balancer

    Why this is correct

    The security group must allow inbound HTTP/HTTPS from the load balancer's security group or CIDR.

  • The instance is in a stopped state

    Why it's wrong here

    The state is running.

  • The instance is not in the same VPC as the load balancer

    Why it's wrong here

    The instance is in the same VPC as shown.

  • The instance does not have a public IP address

    Why it's wrong here

    Instances behind a load balancer can be private.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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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.