Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit
show run | section nat ip nat inside source list 10 interface g0/0 overload access-list 10 permit 192.168.10.0 0.0.0.255
Exhibit: An administrator wants inside hosts in 192.168.10.0/24 to reach the internet using one public IP address on the edge router. Which feature is being used?
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
Static NAT
Static NAT maps one inside address to one outside address.
B
Distractor review
Policy-based routing
That changes forwarding decisions, not address translation.
C
Best answer
PAT overload
The overload keyword indicates PAT using one outside interface address.
D
Distractor review
Port security
Port security applies on switch ports, not this router NAT function.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking static NAT for PAT overload. Static NAT provides a fixed one-to-one mapping between inside and outside IP addresses, which cannot support multiple inside hosts sharing a single public IP. Candidates may also confuse policy-based routing with NAT functions, but policy-based routing only affects forwarding decisions without translating addresses. Additionally, port security applies to switch ports to restrict MAC addresses and does not relate to NAT or internet access. Recognizing that PAT overload uniquely enables many inside hosts to share one public IP by using port numbers prevents this common mistake.
Technical deep dive
How to think about this question
Port Address Translation (PAT), often called NAT overload in Cisco terminology, is a form of Network Address Translation that enables multiple devices on a private network to access external networks using a single public IP address. PAT works by translating the private IP addresses and their source ports into the public IP address and unique port numbers, allowing the router to keep track of each session individually. This method conserves public IP addresses and is widely used in IPv4 networks where public addresses are scarce. In Cisco routers, PAT is configured by applying NAT with the 'overload' keyword on the outside interface. This tells the router to translate multiple inside local addresses to the single inside global address (the public IP) by assigning different source port numbers. When inside hosts initiate connections to the internet, the router modifies the source IP and port, and when responses return, it uses the port number to correctly forward packets back to the originating host. This dynamic translation is essential for enabling many hosts in a private subnet like 192.168.10.0/24 to share one public IP. A common exam trap is confusing PAT overload with static NAT or policy-based routing. Static NAT maps one private IP to one public IP, which cannot support multiple hosts sharing one IP. Policy-based routing influences packet forwarding paths but does not perform address translation. Port security is a Layer 2 feature unrelated to NAT. Understanding these distinctions helps avoid selecting incorrect answers and ensures proper NAT configuration for internet access in Cisco environments.
KKey Concepts to Remember
- PAT (Port Address Translation) allows multiple inside private IP addresses to share a single public IP address by differentiating sessions using Layer 4 port numbers.
- Cisco NAT overload is a common term for PAT, where the router uses one outside interface IP address with multiple port numbers to translate many inside hosts.
- Static NAT creates a one-to-one mapping between a private IP address and a public IP address, which does not support multiple hosts sharing a single public IP.
- Policy-based routing changes packet forwarding decisions based on policies but does not perform IP address translation or NAT functions.
- Port security restricts MAC addresses on switch ports to prevent unauthorized access and is unrelated to NAT or IP address translation on routers.
- PAT overload is essential for conserving public IPv4 addresses by enabling many inside hosts to access the internet using a single public IP.
- The router uses the 'overload' keyword in NAT configuration to enable PAT, allowing multiple simultaneous translations with unique port numbers.
- Understanding the difference between static NAT and PAT overload is critical for correctly configuring internet access for multiple inside hosts.
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?
PAT (Port Address Translation) allows multiple inside private IP addresses to share a single public IP address by differentiating sessions using Layer 4 port numbers.
What is the correct answer to this question?
The correct answer is: PAT overload — When many inside private addresses share one public address and are differentiated by Layer 4 port numbers, the router is using PAT. Cisco documentation often calls this NAT overload.
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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