The answer is that the VPC endpoint has been deleted. When troubleshooting VPC endpoint blackhole state, a blackhole route in a route table indicates that the target resource—in this case, the VPC endpoint (vpce-12345678)—no longer exists or has entered a failed state, causing the route to become a dead end. This occurs because AWS automatically marks routes as blackhole when their target is deleted or becomes unavailable, preventing traffic from being silently dropped. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your understanding of how VPC endpoints interact with route tables and the specific meaning of blackhole states, which is a common trap: many candidates confuse blackhole with a missing route or a routing loop. A reliable memory tip is to think of a blackhole as a “deleted destination”—if the endpoint is gone, the route has nowhere to go, so it turns black.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. 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. The following is an AWS CLI output:
{
"RouteTables": [
{
"RouteTableId": "rtb-12345678",
"Routes": [
{
"DestinationCidrBlock": "10.0.0.0/16",
"GatewayId": "local",
"State": "active"
},
{
"DestinationCidrBlock": "0.0.0.0/0",
"GatewayId": "igw-12345678",
"State": "active"
},
{
"DestinationCidrBlock": "10.0.0.0/8",
"GatewayId": "vpce-12345678",
"State": "blackhole"
}
]
}
]
}
A network engineer is troubleshooting connectivity issues. The route table shows a blackhole route for 10.0.0.0/8 pointing to a VPC endpoint (vpce-12345678). What is the most likely cause of the blackhole state?
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 VPC endpoint (vpce-12345678) has been deleted.
Option B is correct because a blackhole route for a VPC endpoint typically indicates the endpoint has been deleted or is in a failed state. A is incorrect because the VPC CIDR is more specific. C is irrelevant. D is incorrect because blackhole doesn't indicate no route.
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 VPC endpoint (vpce-12345678) has been deleted.
Why this is correct
A deleted endpoint results in a blackhole route.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
The VPC CIDR 10.0.0.0/16 is overlapping with the endpoint route.
Why it's wrong here
Overlap doesn't cause blackhole; the local route takes precedence.
✗
The route table does not have a route to the internet.
Why it's wrong here
There is a route to IGW.
✗
The internet gateway is not attached to the VPC.
Why it's wrong here
IGW is active and not related to endpoint route.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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 ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Network Implementation — This question tests Network Implementation — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The VPC endpoint (vpce-12345678) has been deleted. — Option B is correct because a blackhole route for a VPC endpoint typically indicates the endpoint has been deleted or is in a failed state. A is incorrect because the VPC CIDR is more specific. C is irrelevant. D is incorrect because blackhole doesn't indicate no route.
What should I do if I get this ANS-C01 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 ANS-C01 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.
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