This DBS-C01 practice question tests your understanding of database security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A company is using Amazon DocumentDB (with MongoDB compatibility) for a content management system. The security team requires that all data be encrypted at rest and in transit. The DocumentDB cluster is already encrypted at rest using AWS KMS. To enforce encryption in transit, the security team wants to ensure that all client connections use TLS. The team has enabled the 'tls' parameter in the cluster parameter group. However, a developer reports that they can still connect to the cluster without specifying TLS options using the mongo shell. The developer is connecting from an EC2 instance in the same VPC. The security group for the DocumentDB cluster allows inbound traffic on port 27017 from the EC2 instance's security group. What is the most likely reason the developer can connect without TLS?
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 'tls' parameter was not applied to the cluster because the parameter group was not associated with the cluster or the cluster was not rebooted.
Option B is correct. DocumentDB supports both TLS and non-TLS connections on the same port. Enabling the 'tls' parameter in the parameter group only affects new connections if the client requests TLS; it does not force TLS. To enforce TLS, you must modify the cluster's security group to block non-TLS traffic, or use a different port for TLS. However, DocumentDB does not have a separate port for TLS; the same port can accept both. The parameter 'tls' when set to 'enabled' actually forces TLS for all connections? Actually, in DocumentDB, setting the cluster parameter 'tls' to 'enabled' does enforce TLS; but the developer might be using an older client that does not support TLS. But the question says the developer can connect without specifying TLS options. That suggests that the parameter might not be applied or the cluster was not rebooted. Option A is possible but less likely. Option C is incorrect because TLS is supported. Option D is incorrect because the same VPC does not bypass TLS.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
DocumentDB does not support TLS; it only supports SSL.
The EC2 instance is in the same VPC, so TLS is not enforced for intra-VPC traffic.
Why it's wrong here
TLS enforcement applies regardless of network location.
✗
The developer is using an older version of the mongo shell that does not support TLS.
Why it's wrong here
If the server enforces TLS, the connection would fail, not succeed.
✓
The 'tls' parameter was not applied to the cluster because the parameter group was not associated with the cluster or the cluster was not rebooted.
Why this is correct
Parameter group changes require a reboot to take effect.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DBS-C01 NAT questions on configuration and troubleshooting.
Database Security — This question tests Database Security — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The 'tls' parameter was not applied to the cluster because the parameter group was not associated with the cluster or the cluster was not rebooted. — Option B is correct. DocumentDB supports both TLS and non-TLS connections on the same port. Enabling the 'tls' parameter in the parameter group only affects new connections if the client requests TLS; it does not force TLS. To enforce TLS, you must modify the cluster's security group to block non-TLS traffic, or use a different port for TLS. However, DocumentDB does not have a separate port for TLS; the same port can accept both. The parameter 'tls' when set to 'enabled' actually forces TLS for all connections? Actually, in DocumentDB, setting the cluster parameter 'tls' to 'enabled' does enforce TLS; but the developer might be using an older client that does not support TLS. But the question says the developer can connect without specifying TLS options. That suggests that the parameter might not be applied or the cluster was not rebooted. Option A is possible but less likely. Option C is incorrect because TLS is supported. Option D is incorrect because the same VPC does not bypass TLS.
What should I do if I get this DBS-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DBS-C01 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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