The answer is Port Address Translation (PAT), also known as NAT overload. This is correct because PAT allows multiple internal hosts to share a single inside global IP address by differentiating each session using unique transport-layer port numbers (TCP or UDP), which is exactly what the scenario describes. On the Systems Security Certified Practitioner SSCP exam, this concept tests your understanding of how network address translation conserves public IPv4 addresses, often appearing in questions that contrast PAT with static or dynamic NAT. A common trap is confusing PAT with basic NAT, but remember that NAT only translates IP addresses, while PAT adds port-level multiplexing to enable many-to-one mapping. For a quick memory tip, think of PAT as “Port Address Translation” where the “P” stands for “Port” and “PAT” rhymes with “flat” because it flattens many private IPs into one public IP.
SSCP Network and Communications Security Practice Question
This SSCP practice question tests your understanding of network and communications security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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
Router# show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 203.0.113.10:80 192.168.1.10:80 198.51.100.20:80 198.51.100.20:80
tcp 203.0.113.10:443 192.168.1.10:443 198.51.100.20:443 198.51.100.20:443
tcp 203.0.113.11:80 192.168.1.11:80 198.51.100.30:80 198.51.100.30:80
Refer to the exhibit. A security analyst notices that multiple internal hosts are using the same inside global IP address but different port numbers. Which technology is being used?
Router# show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 203.0.113.10:80 192.168.1.10:80 198.51.100.20:80 198.51.100.20:80
tcp 203.0.113.10:443 192.168.1.10:443 198.51.100.20:443 198.51.100.20:443
tcp 203.0.113.11:80 192.168.1.11:80 198.51.100.30:80 198.51.100.30:80
A
Dynamic NAT
Why wrong: Dynamic NAT uses a pool of public IPs.
B
Static NAT
Why wrong: Static NAT maps one private IP to one public IP.
C
PAT (Port Address Translation)
PAT allows many internal hosts to share a single public IP by differentiating via port numbers.
D
Port forwarding
Why wrong: Port forwarding is used to allow external access to internal services.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
PAT (Port Address Translation)
The scenario describes multiple internal hosts sharing a single inside global IP address but using different port numbers. This is the defining behavior of Port Address Translation (PAT), also known as NAT overload. PAT maps multiple private IP addresses to one public IP by differentiating sessions based on the transport-layer port number (TCP/UDP), allowing many hosts to share a single public address.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
PAT allows many internal hosts to share a single public IP by differentiating via port numbers.
Related concept
Read the scenario before looking for a memorised answer.
✗
Port forwarding
Why it's wrong here
Port forwarding is used to allow external access to internal services.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse PAT with Dynamic NAT, not realizing that Dynamic NAT requires a pool of public IPs and does not allow port-level multiplexing, whereas PAT is specifically designed to allow many-to-one address sharing using port differentiation.
Detailed technical explanation
How to think about this question
PAT operates by modifying the source port number in the TCP/UDP header to a unique value for each session, while keeping the source IP address the same. The NAT device maintains a translation table that tracks the original (private IP, private port) pair and the translated (public IP, public port) pair. In Cisco IOS, PAT is configured using the 'ip nat inside source list ACL interface interface overload' command, and it is essential for conserving IPv4 addresses in enterprise and home networks where the ISP provides only one public IP.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network and Communications Security — This question tests Network and Communications Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: PAT (Port Address Translation) — The scenario describes multiple internal hosts sharing a single inside global IP address but using different port numbers. This is the defining behavior of Port Address Translation (PAT), also known as NAT overload. PAT maps multiple private IP addresses to one public IP by differentiating sessions based on the transport-layer port number (TCP/UDP), allowing many hosts to share a single public address.
What should I do if I get this SSCP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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