SC-100 Design security solutions for infrastructure Practice Question
This SC-100 practice question tests your understanding of design security solutions for infrastructure. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The destination address prefix is 'VirtualNetwork' which allows traffic to all VMs
Option D is correct: The rule allows HTTP (port 80) from the Internet to the VirtualNetwork address prefix, which effectively allows inbound traffic from any public IP to all VMs in the virtual network on port 80. This is overly permissive. Option A is wrong because the rule allows HTTP, not HTTPS. Option B is wrong because the rule allows inbound, not outbound. Option C is wrong because the rule allows Internet, not a specific IP.
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.
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The source address prefix should be a specific IP range
Why it's wrong here
While best practice, the main issue is destination is VirtualNetwork.
The destination address prefix is 'VirtualNetwork' which allows traffic to all VMs
Why this is correct
Should be a specific subnet or IP to restrict access.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
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 SC-100 NAT questions on configuration and troubleshooting.
Design security solutions for infrastructure — This question tests Design security solutions for infrastructure — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The destination address prefix is 'VirtualNetwork' which allows traffic to all VMs — Option D is correct: The rule allows HTTP (port 80) from the Internet to the VirtualNetwork address prefix, which effectively allows inbound traffic from any public IP to all VMs in the virtual network on port 80. This is overly permissive. Option A is wrong because the rule allows HTTP, not HTTPS. Option B is wrong because the rule allows inbound, not outbound. Option C is wrong because the rule allows Internet, not a specific IP.
What should I do if I get this SC-100 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 SC-100 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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