The answer is the missing health check endpoint /health on the web server. This is correct because the user_data script only installs and starts the httpd service but never creates the specific /health path that the load balancer is configured to probe. A load balancer health check failure due to missing endpoint occurs when the target responds on the port but returns a non-200 status code for the configured path, since the web server has no route or file at that location. On the CompTIA Cloud+ CV0-004 exam, this tests your understanding that health checks verify both service availability and endpoint logic, not just that the server is running. A common trap is assuming a running web server automatically passes all health checks, but the path must explicitly exist. Memory tip: “Health checks need a home—if the path isn’t there, the check will roam.”
CV0-004 Operations and Support Practice Question
This CV0-004 practice question tests your understanding of operations and support. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
```
resource "aws_instance" "web" {
ami = "ami-12345678"
instance_type = "t2.micro"
subnet_id = "subnet-abc123"
vpc_security_group_ids = ["sg-xyz789"]
user_data = <<-EOF
#!/bin/bash
yum install -y httpd
service httpd start
EOF
}
resource "aws_lb_target_group" "web_tg" {
name = "web-tg"
port = 80
protocol = "HTTP"
vpc_id = "vpc-111111"
health_check {
path = "/health"
}
}
resource "aws_lb_listener" "web_listener" {
load_balancer_arn = aws_lb.web.arn
port = 80
default_action {
type = "forward"
target_group_arn = aws_lb_target_group.web_tg.arn
}
}
```
A cloud engineer deployed the infrastructure shown. The load balancer's health checks are failing for the EC2 instance. Which of the following is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The health check endpoint /health does not exist on the web server.
Option A is correct because the health check path '/health' is not created by the user_data script, which only installs httpd and starts it, but does not create the health check endpoint. Option B is wrong because the security group is attached. Option C is wrong because the subnet is specified. Option D is wrong because the user_data script starts httpd.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 web server is not running HTTP.
Why it's wrong here
User data starts httpd service.
✓
The health check endpoint /health does not exist on the web server.
Why this is correct
The user_data script does not create a /health page; it only installs httpd.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
The security group does not allow traffic from the load balancer.
Why it's wrong here
Security group is attached, but the issue is likely the missing health check.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CV0-004 subnetting questions on CIDR, address ranges, and subnet selection.
Operations and Support — This question tests Operations and Support — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The health check endpoint /health does not exist on the web server. — Option A is correct because the health check path '/health' is not created by the user_data script, which only installs httpd and starts it, but does not create the health check endpoint. Option B is wrong because the security group is attached. Option C is wrong because the subnet is specified. Option D is wrong because the user_data script starts httpd.
What should I do if I get this CV0-004 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CV0-004 subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Refer to the exhibit. A cloud load balancer is returning 502 Bad Gateway errors to clients. What is the most likely cause?
medium
A.The load balancer's SSL certificate is invalid.
B.The security group allows inbound traffic from the load balancer.
C.The DNS record points to the wrong IP.
✓ D.The backend web servers are not responding correctly.
Why D: A 502 Bad Gateway error indicates that the load balancer (acting as a proxy or gateway) received an invalid or no response from the upstream backend web servers. This typically occurs when the backend servers are overloaded, have crashed, or are misconfigured (e.g., incorrect health check path, application pool failure). The load balancer successfully forwards the request but fails to get a valid HTTP response, triggering the 502 error.
Last reviewed: Jun 24, 2026
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