- A
All traffic from 192.168.1.0/24 is translated to 203.0.113.1 using PAT.
The 'overload' keyword enables PAT, and the ACL matches the inside network.
- B
Only traffic from 192.168.1.1 is translated to 203.0.113.1 using PAT.
Why wrong: The ACL permits the entire /24 subnet, not just the router's interface IP.
- C
Traffic is translated using static NAT to 203.0.113.1.
Why wrong: The command uses 'ip nat inside source list' which is dynamic NAT, not static.
- D
The configuration is incomplete; a NAT pool is required for dynamic translation.
Why wrong: When using an interface with overload, no pool is needed; the interface IP is used.
Question 2,084 of 2,152
Effect of PAT Overload Configuration
This 300-410 practice question tests your understanding of nat and pat. 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. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
Consider the following partial configuration on a Cisco IOS-XE router:
interface GigabitEthernet0/0 ip address 192.168.1.1 255.255.255.0 ip nat inside
!
interface GigabitEthernet0/1 ip address 203.0.113.1 255.255.255.0 ip nat outside
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload access-list 1 permit 192.168.1.0 0.0.0.255
What is the effect of this configuration?
Quick Answer
The answer is that all traffic from the 192.168.1.0/24 network is translated to the single public IP address 203.0.113.1 using PAT (Port Address Translation). This is correct because the `ip nat inside source list 1 interface GigabitEthernet0/1 overload` command binds the NAT pool to the outside interface’s IP address and enables port multiplexing, allowing multiple internal hosts to share one public IP by differentiating sessions via unique source ports. On the Cisco CCNP ENARSI 300-410 exam, this configuration tests your understanding of the PAT overload configuration effect, specifically how the `overload` keyword enables many-to-one translation without a dedicated NAT pool. A common trap is forgetting that the access list defines which inside traffic is eligible—here, only the 192.168.1.0/24 subnet is translated, not all traffic. Memory tip: think of PAT as a “party line”—everyone shares the same phone number, but each conversation gets a unique extension (port).
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
All traffic from 192.168.1.0/24 is translated to 203.0.113.1 using PAT.
The configuration uses an ACL (access-list 1) to match traffic from the 192.168.1.0/24 subnet, and the 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' command translates all matching source IP addresses to the single IP address 203.0.113.1 (the outside interface IP) using Port Address Translation (PAT). This is a classic dynamic NAT overload configuration, where multiple internal hosts share one public IP by multiplexing on source ports.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
All traffic from 192.168.1.0/24 is translated to 203.0.113.1 using PAT.
- ✗
Only traffic from 192.168.1.1 is translated to 203.0.113.1 using PAT.
Why it's wrong here
The ACL permits the entire /24 subnet, not just the router's interface IP.
- ✗
Traffic is translated using static NAT to 203.0.113.1.
Why it's wrong here
The command uses 'ip nat inside source list' which is dynamic NAT, not static.
- ✗
The configuration is incomplete; a NAT pool is required for dynamic translation.
Why it's wrong here
When using an interface with overload, no pool is needed; the interface IP is used.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between 'ip nat inside source list <acl> interface <interface> overload' (dynamic PAT using the interface IP) and configurations that require a NAT pool or static mapping, leading candidates to mistakenly think a pool is mandatory for any dynamic translation.
Trap categories for this question
Command / output trap
The command uses 'ip nat inside source list' which is dynamic NAT, not static.
Detailed technical explanation
How to think about this question
Under the hood, PAT (also known as NAT overload) creates a translation table that maps each internal (private IP, source port) tuple to the single public IP with a unique source port number, as defined in RFC 2663. This allows up to 65,536 simultaneous sessions per public IP (theoretical limit, often lower in practice). A common real-world scenario is a small office using a single public IP for all internal users to access the internet, where the router must track each session's port to correctly demultiplex return traffic.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Visual reference
Quick reference
IPv4 Address Class Summary
| Class | First Octet Range | Default Mask | Networks | Hosts per Network |
|---|---|---|---|---|
| A | 1–126 | /8 (255.0.0.0) | 126 | 16,777,214 |
| B | 128–191 | /16 (255.255.0.0) | 16,384 | 65,534 |
| C | 192–223 | /24 (255.255.255.0) | 2,097,152 | 254 |
| D | 224–239 | N/A | Multicast groups | — |
| E | 240–255 | N/A | Reserved / experimental | — |
127.x.x.x is reserved for loopback. Modern networks use CIDR (classless) rather than classful addressing.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 300-410 question test?
NAT and PAT — This question tests NAT and PAT — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: All traffic from 192.168.1.0/24 is translated to 203.0.113.1 using PAT. — The configuration uses an ACL (access-list 1) to match traffic from the 192.168.1.0/24 subnet, and the 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' command translates all matching source IP addresses to the single IP address 203.0.113.1 (the outside interface IP) using Port Address Translation (PAT). This is a classic dynamic NAT overload configuration, where multiple internal hosts share one public IP by multiplexing on source ports.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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