- A
All inside hosts are translated to the first pool address only.
Why wrong: With overload, the router can use any address in the pool, not just the first.
- B
Each inside host gets a unique pool address without port translation.
Why wrong: The 'overload' keyword enables PAT, so multiple hosts share pool addresses.
- C
Inside hosts matching ACL 10 are translated to addresses in the pool using PAT.
This correctly describes the configuration: dynamic NAT with overload.
- D
The prefix-length 28 is invalid; a netmask must be used instead.
Why wrong: Both 'netmask' and 'prefix-length' are valid in the ip nat pool command.
Question 1,191 of 2,152
How to Configure Dynamic NAT with a Pool and PAT (Overload)
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.
Given this configuration:
ip nat pool GLOBAL 203.0.113.1 203.0.113.10 prefix-length 28 ip nat inside source list 10 pool GLOBAL overload access-list 10 permit 10.0.0.0 0.255.255.255
What is the effect?
Quick Answer
The correct answer is that inside hosts matching ACL 10 are translated to addresses in the pool using PAT. This configuration combines dynamic NAT with a pool and overload, meaning the router will dynamically assign one of the 14 usable addresses from the GLOBAL pool (203.0.113.1 through 203.0.113.10, with a /28 prefix) but then apply port address translation to allow multiple internal hosts to share a single pool address simultaneously. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your understanding of how the overload keyword modifies dynamic NAT behavior—without it, each translation would consume a unique pool address until exhaustion, but with overload, the router multiplexes sessions using source ports. A common trap is confusing this with static NAT or assuming the pool must be fully consumed before PAT kicks in; in reality, PAT is applied immediately to all translations. Memory tip: think of "pool + overload" as "one pool address, many inside hosts"—the overload keyword is the key that unlocks port multiplexing.
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
✓
Inside hosts matching ACL 10 are translated to addresses in the pool using PAT.
The configuration uses `ip nat inside source list 10 pool GLOBAL overload`, which combines a NAT pool with the `overload` keyword to enable Port Address Translation (PAT). ACL 10 permits all 10.0.0.0/8 addresses, so inside hosts matching this ACL are translated to the pool addresses (203.0.113.1–203.0.113.10) with port multiplexing, allowing many hosts to share the same public IP. This is the standard Cisco PAT behavior, making option C correct.
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 inside hosts are translated to the first pool address only.
Why it's wrong here
With overload, the router can use any address in the pool, not just the first.
- ✗
Each inside host gets a unique pool address without port translation.
Why it's wrong here
The 'overload' keyword enables PAT, so multiple hosts share pool addresses.
- ✓
Inside hosts matching ACL 10 are translated to addresses in the pool using PAT.
Why this is correct
This correctly describes the configuration: dynamic NAT with overload.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The prefix-length 28 is invalid; a netmask must be used instead.
Why it's wrong here
Both 'netmask' and 'prefix-length' are valid in the ip nat pool command.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `overload` with static NAT or assume `prefix-length` is invalid, but Cisco explicitly tests the understanding that `overload` enables PAT and that `prefix-length` is a valid syntax for defining the subnet mask in NAT pools.
Trap categories for this question
Keyword trap
The 'overload' keyword enables PAT, so multiple hosts share pool addresses.
Command / output trap
Both 'netmask' and 'prefix-length' are valid in the ip nat pool command.
Detailed technical explanation
How to think about this question
Under the hood, PAT creates an extended translation entry that includes the inside global IP address and a unique Layer 4 port number (e.g., TCP/UDP), allowing up to ~65,000 simultaneous sessions per public IP. The `overload` keyword modifies the NAT translation table to track these port mappings, and the pool addresses are used in a round-robin or least-used fashion depending on the Cisco IOS version. A real-world scenario is a branch office with hundreds of users sharing a small pool of public IPs, where PAT is essential to conserve IPv4 address space.
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
What to study next
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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: Inside hosts matching ACL 10 are translated to addresses in the pool using PAT. — The configuration uses `ip nat inside source list 10 pool GLOBAL overload`, which combines a NAT pool with the `overload` keyword to enable Port Address Translation (PAT). ACL 10 permits all 10.0.0.0/8 addresses, so inside hosts matching this ACL are translated to the pool addresses (203.0.113.1–203.0.113.10) with port multiplexing, allowing many hosts to share the same public IP. This is the standard Cisco PAT behavior, making option C correct.
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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