Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Users on the inside network can browse the web, but the company now needs an internal web server at 192.168.10.50 to be reachable consistently from outside using one public IP address. Which design is most appropriate?
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
Best answer
Use static NAT for the server and continue using PAT for user outbound access.
This is correct because static NAT provides a stable public mapping for the server, while PAT still supports many outbound users.
B
Distractor review
Use PAT only for everything, including the published server.
This is wrong because PAT does not provide the same predictable one-to-one public identity expected for a published server.
C
Distractor review
Disable NAT because private IPv4 addresses are Internet-routable.
This is wrong because private IPv4 addresses are not routable on the public Internet.
D
Distractor review
Use DHCP relay for the server to make it reachable from outside.
This is wrong because DHCP relay is unrelated to public reachability for the server.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting PAT for both outbound and inbound traffic, mistakenly believing PAT can provide a stable public IP for a server. PAT dynamically assigns ports for outbound sessions but does not guarantee a fixed public IP and port combination for inbound connections. This leads to unpredictable external access to the internal server, which fails the requirement for consistent reachability. Another trap is disabling NAT entirely, which ignores that private IPv4 addresses are not routable on the public Internet, making the server unreachable externally. Misunderstanding DHCP relay as a solution for public reachability is also a frequent error, as DHCP relay only forwards DHCP requests and does not affect NAT or routing.
Technical deep dive
How to think about this question
Network Address Translation (NAT) is a fundamental IP service that modifies IP address information in packet headers while in transit across a routing device. Static NAT creates a one-to-one mapping between a private internal IP address and a public IP address, allowing external hosts to consistently reach an internal server using a fixed public IP. In contrast, Port Address Translation (PAT) allows multiple internal hosts to share a single public IP address by differentiating sessions using port numbers, which is ideal for outbound client connections but unsuitable for inbound server accessibility. When designing NAT for a network with both outbound client browsing and inbound server accessibility, the decision hinges on predictability and address conservation. PAT efficiently conserves public IP addresses for outbound traffic by multiplexing many clients behind one IP. However, inbound access to an internal server requires a stable, predictable public IP mapping, which only static NAT can provide. Therefore, the best practice is to use static NAT for the internal web server to ensure consistent external reachability, while continuing to use PAT for general user outbound internet access. A common exam trap is confusing PAT’s role and assuming it can provide reliable inbound access to a server. PAT dynamically assigns ports and does not guarantee a fixed public IP and port combination for inbound connections, making it unsuitable for hosting services. Additionally, disabling NAT or using DHCP relay does not solve inbound reachability issues; private IPs are not routable on the internet, and DHCP relay only forwards DHCP requests, not public traffic. Understanding these distinctions is critical for correct NAT design and passing the CCNA exam.
KKey Concepts to Remember
- Static NAT creates a fixed one-to-one mapping between an internal private IP and a public IP, enabling consistent inbound access to internal servers.
- PAT allows multiple internal clients to share a single public IP address by differentiating sessions with port numbers, optimizing outbound internet access.
- Inbound access to internal servers requires static NAT because PAT does not provide predictable public IP and port mappings for external clients.
- Private IPv4 addresses are not routable on the public Internet, so NAT is necessary to translate these addresses for external communication.
- DHCP relay forwards DHCP requests between clients and servers but does not affect public reachability or NAT mappings.
- Using static NAT for servers and PAT for client outbound traffic balances address conservation with predictable inbound access.
- PAT is unsuitable for hosting services because it dynamically assigns ports and cannot guarantee a stable public endpoint for inbound connections.
- Correct NAT design separates the needs of outbound client browsing and inbound server publishing to ensure both function properly.
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 creates a fixed one-to-one mapping between an internal private IP and a public IP, enabling consistent inbound access to internal servers.
What is the correct answer to this question?
The correct answer is: Use static NAT for the server and continue using PAT for user outbound access. — The best design is static NAT for the server while continuing to use PAT for general user outbound traffic. In plain language, user browsing and server publishing are two different requirements. PAT is great for letting many inside users share one public address for outbound access. But a server that outside clients must find reliably needs a fixed one-to-one public identity. That is exactly what static NAT provides. This is an important design distinction. PAT solves address conservation for many clients. Static NAT solves predictability for inbound access to a specific internal system. The strongest answer is the one that uses each NAT method for the job it fits best.
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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