Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A branch router uses PAT for Internet access. Users can browse out, but the administrator wants a specific internal web server to be reachable from outside on a consistent public address. Which design fits that requirement best?
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 PAT for general user outbound traffic.
This is correct because static NAT gives the server a fixed public identity while PAT supports many internal users.
B
Distractor review
Use only PAT for everything, including predictable outside server reachability.
This is wrong because PAT does not provide the same stable one-to-one outside identity expected for a published server.
C
Distractor review
Disable NAT entirely because private IPv4 addresses are Internet-routable.
This is wrong because private IPv4 addresses are not Internet-routable.
D
Distractor review
Use DHCP relay to publish the server externally.
This is wrong because DHCP relay is unrelated to public server reachability.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting PAT alone to provide external access to an internal server. While PAT efficiently supports many users sharing one public IP for outbound traffic, it does not assign a fixed public IP to any internal host. This means the server’s public identity changes dynamically, preventing reliable inbound connections. Candidates often confuse PAT’s port translation with static IP mapping, overlooking that servers need static NAT for consistent external reachability. Misunderstanding this distinction leads to incorrect answers and design flaws in real networks.
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, allowing multiple devices on a private network to access external networks using fewer public IP addresses. Port Address Translation (PAT), a form of dynamic NAT, enables many internal hosts to share a single public IP address by differentiating sessions through unique port numbers. However, PAT does not provide a fixed public IP for any internal device, which is essential for servers that must be reachable from the Internet. Static NAT creates a one-to-one mapping between a private IP address and a public IP address, ensuring that the internal server always appears at the same public IP externally. This predictability is crucial for services like web servers that require consistent accessibility. In a mixed NAT environment, static NAT is used for servers needing stable public identities, while PAT handles general outbound traffic from multiple users, optimizing IP address usage and maintaining connectivity. A common exam trap is assuming that PAT alone can provide stable inbound access to internal servers, which it cannot because PAT dynamically assigns ports and does not reserve a fixed public IP for any host. Practically, network administrators combine static NAT for servers with PAT for user devices to balance address conservation and service availability, reflecting real-world Cisco network design principles tested in the CCNA exam.
KKey Concepts to Remember
- Static NAT creates a fixed one-to-one mapping between a private IP address and a public IP address, enabling predictable external access to internal servers.
- PAT allows multiple internal hosts to share a single public IP address by differentiating sessions using unique port numbers for outbound traffic.
- A server requiring consistent reachability from outside must use static NAT to maintain a stable public IP address, unlike PAT which is dynamic and port-based.
- Mixed NAT configurations combine static NAT for inbound server accessibility with PAT for outbound user traffic to optimize IP address usage.
- Private IPv4 addresses are not routable on the Internet and require NAT to communicate with external networks.
- DHCP relay is unrelated to NAT and does not influence public accessibility of internal servers.
- Using only PAT for all traffic fails to provide a stable public IP for servers, making it unsuitable for hosting externally reachable services.
- Cisco routers support simultaneous static NAT and PAT configurations to meet different network requirements within the same environment.
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 a private IP address and a public IP address, enabling predictable external access to internal servers.
What is the correct answer to this question?
The correct answer is: Use static NAT for the server and PAT for general user outbound traffic. — The best design is to use static NAT for the internal web server while continuing to use PAT for general user outbound access. In plain language, PAT is ideal for many inside users sharing one public address for ordinary outbound traffic, but a server that must be reachable predictably from the outside needs a fixed public identity. Static NAT provides that one-to-one mapping. This is a practical mixed-design scenario. The network can use PAT for user convenience and address conservation while still reserving a stable translation for a server that external clients need to find reliably. The correct answer recognizes that different NAT methods can serve different purposes in the same environment.
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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