Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
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?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
A default route on the inside host
The inside host can already reach the internet, so basic routing is present.
B
Best answer
An ACL permit entry allowing TCP port 80 or 443 to the translated address
NAT alone does not override an inbound filtering policy.
C
Distractor review
PAT overload on the outside interface
PAT is not required for a static server publish scenario.
D
Distractor review
DHCP relay toward the web server
That has nothing to do with inbound published web access.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that configuring static NAT alone guarantees inbound access to a published web server. Many candidates forget that Cisco routers and firewalls use ACLs to filter traffic, and inbound ACLs on the outside interface must explicitly permit traffic to the translated IP and relevant ports like TCP 80 or 443. Without these ACL entries, the router blocks inbound connections despite correct NAT translation. This oversight leads to confusion when inside hosts can reach the internet, but external clients cannot access the published server. Remember, NAT and ACLs work together to control traffic flow.
Technical deep dive
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
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 has to be permitted by any inbound ACL or firewall policy on the outside interface. Many troubleshooting questions hinge on translation being present while a policy still blocks the flow.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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