The answer is an ACL permit entry allowing TCP port 80 or 443 to the translated address. Static NAT correctly maps the public IP to the private web server, but it only handles the translation; it does not automatically permit traffic. An inbound ACL on the outside interface acts as a firewall, and without an explicit permit for the web traffic, the packets are dropped even after translation. On the CCNA 200-301 v2 exam, this scenario tests your understanding that NAT and ACLs are separate functions—a common trap is assuming static NAT alone opens the door. Remember, NAT translates, ACLs filter. A useful memory tip: “NAT maps, ACL taps”—the ACL must tap the port open for inbound traffic to reach the server.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. A key principle to apply: static NAT translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host.. 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
ip nat inside source static 192.168.20.10 198.51.100.10
interface g0/0
ip nat outside
ip access-group OUTSIDE-IN in
Exhibit: Hosts on the inside network can reach the internet, but inbound connections to a published web server fail. Static NAT is configured. What is the most likely missing piece?
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
✓
An ACL permit entry allowing TCP port 80 or 443 to the translated address
Static NAT provides the address translation, but traffic still must be permitted by an inbound ACL or firewall policy on the outside interface. Option A is incorrect because a default route on the inside host affects outbound traffic, not inbound connections. Option C is wrong since PAT overload is for many-to-one translation and is not required here, and it would not block inbound traffic if static NAT is already configured. Option D is incorrect because DHCP relay does not influence inbound access to a web server; it only forwards DHCP requests from clients to a remote DHCP server.
Key principle: Static NAT translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
A default route on the inside host
Why it's wrong here
The inside host can already reach the internet, so basic routing is present.
When this WOULD be correct
In a scenario where the question specifies that hosts on the inside network cannot reach any external resources, and the configuration is missing a default route on the inside host, this option would be correct. For example, if the question stated that internal users cannot access the internet at all, then a default route would be necessary.
✓
An ACL permit entry allowing TCP port 80 or 443 to the translated address
Why this is correct
NAT alone does not override an inbound filtering policy.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host.
✗
PAT overload on the outside interface
Why it's wrong here
PAT is not required for a static server publish scenario.
When this WOULD be correct
In a different scenario where multiple internal hosts need to share a single public IP address for outbound connections, a question might ask about the configuration needed to enable this. In that case, the correct answer could be PAT overload on the outside interface to allow multiple hosts to access the internet simultaneously.
✗
DHCP relay toward the web server
Why it's wrong here
That has nothing to do with inbound published web access.
When this WOULD be correct
In a different scenario where a web server is on a different subnet and requires DHCP for IP assignment, a question might ask about enabling communication between the server and clients. In this case, a DHCP relay would be necessary to forward DHCP requests from clients to the server's subnet.
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.
✓An ACL permit entry allowing TCP port 80 or 443 to the translated addressCorrect answer▾
Why this is correct
NAT alone does not override an inbound filtering policy.
✗A default route on the inside hostWrong answer — click to see why▾
Why this is wrong here
A default route on the inside host is not relevant to the failure of inbound connections to the web server; it only affects outbound traffic. The issue here is related to access control for incoming connections, not routing on the inside host.
★ When this WOULD be the correct answer
In a scenario where the question specifies that hosts on the inside network cannot reach any external resources, and the configuration is missing a default route on the inside host, this option would be correct. For example, if the question stated that internal users cannot access the internet at all, then a default route would be necessary.
Why candidates choose this
Candidates may confuse the need for proper routing with the issue of inbound connections, leading them to believe that a default route is necessary for all types of connectivity, including inbound traffic.
✗PAT overload on the outside interfaceWrong answer — click to see why▾
Why this is wrong here
PAT overload on the outside interface is not relevant to the failure of inbound connections to a published web server, as static NAT is already configured for the server's IP address. PAT is used for dynamic address translation, which does not apply here.
★ When this WOULD be the correct answer
In a different scenario where multiple internal hosts need to share a single public IP address for outbound connections, a question might ask about the configuration needed to enable this. In that case, the correct answer could be PAT overload on the outside interface to allow multiple hosts to access the internet simultaneously.
Why candidates choose this
Candidates may choose this option because they associate NAT configurations with address translation and might overlook the specific context of static NAT versus PAT, leading to confusion about their roles in inbound and outbound traffic.
✗DHCP relay toward the web serverWrong answer — click to see why▾
Why this is wrong here
DHCP relay is not relevant in this scenario because it pertains to forwarding DHCP requests, not facilitating inbound connections to a web server. The issue here is related to NAT and access control, not IP address assignment.
★ When this WOULD be the correct answer
In a different scenario where a web server is on a different subnet and requires DHCP for IP assignment, a question might ask about enabling communication between the server and clients. In this case, a DHCP relay would be necessary to forward DHCP requests from clients to the server's subnet.
Why candidates choose this
Candidates may confuse DHCP relay with general network connectivity issues, mistakenly believing that it could help resolve inbound connection problems to a web server, especially if they have encountered similar scenarios in their studies.
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
Many candidates assume that static NAT alone guarantees inbound access, forgetting that an inbound ACL on the outside interface must explicitly permit the traffic.
Trap categories for this question
Scenario analysis trap
PAT is not required for a static server publish scenario.
Detailed technical explanation
How to think about this question
Network Address Translation (NAT) is a fundamental technology in Cisco networking that translates private IP addresses to public IP addresses, enabling internal hosts to communicate with external networks like the internet. Static NAT specifically maps a single inside local IP address to a single inside global IP address, allowing inbound and outbound traffic to use consistent IP addresses. This is essential for hosting services such as web servers, where external clients must reach a known public IP address that translates to the internal server.
While static NAT ensures the IP address translation is correct, Cisco devices also use Access Control Lists (ACLs) to filter traffic based on rules. Inbound ACLs on the outside interface must explicitly permit traffic destined for the translated IP address and relevant ports (e.g., TCP port 80 for HTTP or 443 for HTTPS). Without these ACL entries, the router or firewall will block incoming connections despite successful NAT translation, causing published services to be unreachable from the internet.
A common exam trap is assuming that NAT alone is sufficient for inbound connectivity. Candidates often overlook the role of ACLs in filtering traffic, leading to failed inbound connections even when static NAT is configured correctly. Practically, network engineers must verify both NAT translation and ACL permissions to ensure published servers are accessible externally. This layered security approach protects internal networks while allowing controlled access to services.
KKey Concepts to Remember
Static NAT translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host.
Inbound ACLs on the router's outside interface must explicitly permit traffic to the translated IP address and specific service ports like TCP 80 or 443.
NAT performs address translation but does not override or bypass ACL filtering policies configured on interfaces.
Without an ACL permit entry for inbound traffic, published services behind static NAT will be unreachable despite correct address translation.
Inside hosts require proper routing to reach the internet, but inbound access depends on both NAT and ACL configurations.
PAT overload is not necessary for static NAT scenarios where a single internal server is published to the internet.
DHCP relay configuration is unrelated to inbound NAT or ACL issues affecting published web servers.
Troubleshooting inbound connectivity issues requires verifying both NAT translation tables and ACL rules on the router or firewall.
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 translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host.
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 translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host., 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 translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host..
What is the correct answer to this question?
The correct answer is: An ACL permit entry allowing TCP port 80 or 443 to the translated address — Static NAT provides the address translation, but traffic still must be permitted by an inbound ACL or firewall policy on the outside interface. Option A is incorrect because a default route on the inside host affects outbound traffic, not inbound connections. Option C is wrong since PAT overload is for many-to-one translation and is not required here, and it would not block inbound traffic if static NAT is already configured. Option D is incorrect because DHCP relay does not influence inbound access to a web server; it only forwards DHCP requests from clients to a remote DHCP server.
What should I do if I get this 200-301 question wrong?
Review static NAT translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host., 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: "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 translates a single inside local IP address to a single inside global IP address, enabling consistent inbound and outbound communication for a host.
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