The answer is Static NAT. This is the correct choice because it establishes a fixed, one-to-one mapping between an internal server’s private IP and a specific public IP address, ensuring that the server is consistently reachable from the internet using that known public address. On the CCNA 200-301 v2 exam, this question tests your understanding of how different NAT types handle inbound versus outbound traffic; a common trap is confusing Static NAT with Dynamic NAT or PAT, but remember that only Static NAT guarantees a permanent, predictable public identity for an inside server. The exam often frames this scenario as a company needing a web or email server accessible from outside without address changes. A helpful memory tip is to think of “Static” as “staying the same”—the public IP never changes, just like a street address for a house.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability.. 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 wants a server on the inside network to be reachable consistently from outside using one known public IP address. Which NAT approach best fits that goal?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Static NAT
Static NAT best fits that goal because it creates a fixed, predictable one-to-one mapping between the internal server and a public address. In plain language, outside systems always know which public IP represents that server. This predictability is exactly what is needed when a service must be reachable consistently from the outside.
PAT is better suited for many outbound clients sharing one address, not for presenting one inside server with a permanent public identity. Dynamic NAT from a pool can also vary depending on design. The correct answer is the one that provides the most stable and direct one-to-one mapping.
Key principle: Static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Static NAT
Why this is correct
This is correct because static NAT provides a permanent one-to-one mapping suitable for a reachable internal server.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability.
✗
PAT overload only
Why it's wrong here
This is wrong because PAT is mainly intended for many sessions sharing fewer public addresses.
When this WOULD be correct
In a question where the requirement is to allow multiple internal servers to access the Internet using a single public IP address without needing consistent external access to any specific server, PAT overload would be the correct choice.
✗
No NAT at all, because private IPv4 addresses are Internet-routable
Why it's wrong here
This is wrong because private IPv4 addresses are not Internet-routable.
When this WOULD be correct
In a scenario where a question asks about a network setup that uses only public IP addresses throughout, and the focus is on internal routing without the need for NAT, then this option could be correct. For example, a question might specify a fully public IPv6 network where NAT is unnecessary.
✗
DHCP relay
Why it's wrong here
This is wrong because DHCP relay is unrelated to public reachability through NAT.
When this WOULD be correct
If the question asked about enabling DHCP functionality for devices on a network that require IP address assignment from a remote DHCP server, then DHCP relay would be the correct answer, as it facilitates the communication necessary for DHCP in such scenarios.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Static NATCorrect answer▾
Why this is correct
This is correct because static NAT provides a permanent one-to-one mapping suitable for a reachable internal server.
✗PAT overload onlyWrong answer — click to see why▾
Why this is wrong here
PAT overload allows multiple internal devices to share a single public IP address, but it does not provide a consistent mapping for a specific internal server, which is required in this scenario.
★ When this WOULD be the correct answer
In a question where the requirement is to allow multiple internal servers to access the Internet using a single public IP address without needing consistent external access to any specific server, PAT overload would be the correct choice.
Why candidates choose this
Candidates may confuse PAT overload with static NAT, thinking that since it allows multiple connections, it could also provide consistent external access, leading them to select this option incorrectly.
✗No NAT at all, because private IPv4 addresses are Internet-routableWrong answer — click to see why▾
Why this is wrong here
Private IPv4 addresses are not routable on the Internet; they require NAT to communicate externally. Therefore, stating that no NAT is needed contradicts the requirement for consistent external reachability using a public IP address.
★ When this WOULD be the correct answer
In a scenario where a question asks about a network setup that uses only public IP addresses throughout, and the focus is on internal routing without the need for NAT, then this option could be correct. For example, a question might specify a fully public IPv6 network where NAT is unnecessary.
Why candidates choose this
Candidates may be tempted by this option due to a misunderstanding of private versus public IP address functionality, leading them to incorrectly assume that private addresses can be used directly for external access.
✗DHCP relayWrong answer — click to see why▾
Why this is wrong here
DHCP relay is not relevant to the goal of making a server reachable from outside using a consistent public IP address. It is used to forward DHCP requests from clients to a DHCP server, not for NAT purposes.
★ When this WOULD be the correct answer
If the question asked about enabling DHCP functionality for devices on a network that require IP address assignment from a remote DHCP server, then DHCP relay would be the correct answer, as it facilitates the communication necessary for DHCP in such scenarios.
Why candidates choose this
Candidates may confuse DHCP relay with NAT concepts, thinking that it could somehow assist in making internal servers accessible externally, due to a lack of clarity on the distinct roles of NAT and DHCP in network configurations.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting PAT overload as the solution for making an internal server reachable from outside. PAT is designed for multiple internal clients to share a single public IP for outbound connections, not for providing a fixed public IP to a server. Another common mistake is thinking private IP addresses can be accessed directly from the Internet without NAT, which is incorrect because private IPs are non-routable externally. Misunderstanding DHCP relay as related to NAT or public reachability is also a trap; DHCP relay only forwards DHCP requests and does not affect NAT mappings or external accessibility.
Detailed technical explanation
How to think about this question
Network Address Translation (NAT) is a fundamental IP service used to translate private IP addresses to public IP addresses, enabling internal devices to communicate with external networks. Static NAT specifically provides a fixed, one-to-one mapping between an internal private IP address and a public IP address. This mapping does not change over time, making it ideal for servers that need to be consistently reachable from the Internet, such as web servers or mail servers.
When deciding which NAT method to use, the key consideration is whether the internal device requires a permanent public identity. Static NAT guarantees this by reserving a unique public IP address for the internal server, ensuring external clients always use the same IP to reach it. In contrast, dynamic NAT assigns public IPs from a pool on a first-come, first-served basis, which can change over time and is unsuitable for servers. PAT overload allows many internal hosts to share a single public IP by differentiating sessions with port numbers, but it does not provide a fixed public IP for inbound connections.
A common exam trap is confusing PAT overload with static NAT. While PAT is efficient for outbound client traffic, it does not support inbound connections to a specific internal server with a consistent public IP. Another trap is assuming private IP addresses are routable on the Internet, which they are not. Understanding these distinctions is critical for configuring NAT correctly in Cisco environments and for answering CCNA questions accurately. Practically, static NAT simplifies firewall rules and external DNS configurations because the server’s public IP is always known and stable.
KKey Concepts to Remember
Static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability.
PAT (Port Address Translation) allows multiple internal hosts to share a single public IP address by differentiating sessions using port numbers, but does not provide fixed mappings.
Private IPv4 addresses are not routable on the public Internet and require NAT to be accessible from outside networks.
DHCP relay forwards DHCP requests between clients and servers across different IP networks and does not affect NAT or public reachability of internal servers.
Static NAT is essential when an internal server must be accessible from the Internet using a known, fixed public IP address for services like web hosting or remote access.
Dynamic NAT maps internal addresses to public addresses from a pool temporarily, which can cause inconsistent external IP mappings for servers.
PAT overload is optimized for outbound client traffic, not for inbound connections to a specific internal server.
Using static NAT simplifies firewall and access control configurations because the external IP address of the server is predictable and constant.
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
Static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Services and Security — This question tests Network Services and Security — Static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability..
What is the correct answer to this question?
The correct answer is: Static NAT — Static NAT best fits that goal because it creates a fixed, predictable one-to-one mapping between the internal server and a public address. In plain language, outside systems always know which public IP represents that server. This predictability is exactly what is needed when a service must be reachable consistently from the outside.
PAT is better suited for many outbound clients sharing one address, not for presenting one inside server with a permanent public identity. Dynamic NAT from a pool can also vary depending on design. The correct answer is the one that provides the most stable and direct one-to-one mapping.
What should I do if I get this 200-301 question wrong?
Review static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability., then practise related 200-301 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Static NAT creates a permanent one-to-one mapping between a private internal IP address and a public IP address, ensuring consistent external reachability.
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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. A company wants an internal web server to be reachable consistently from the Internet using one known public IPv4 address. Which NAT approach best fits that requirement?
hard
✓ A.Static NAT
B.PAT overload
C.No NAT, because private IPv4 addresses are publicly routable
D.DHCP relay
Why A: Static NAT is the best fit because it creates a fixed one-to-one relationship between the inside server and the public address. In practical terms, outside clients need a stable public identity for the server. They cannot rely on a translated address that changes session by session. Static NAT gives that predictability.
This is different from PAT, which is designed for many inside users sharing fewer public addresses for outbound traffic. The question is about publishing a server, not conserving addresses for client browsing. That is why static NAT is the strongest answer.
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