The answer is that the router is performing Port Address Translation (PAT). This is confirmed by the output showing 5 active dynamic translations, all marked as "extended," which is the key indicator of PAT because extended translations track both IP address and port number, unlike basic translations that only map one internal IP to one external IP. The pool POOL1 contains 10 addresses, yet only 5 are in use, and the "Hits: 1234" versus "Misses: 5" shows that most packets find an existing translation while misses trigger new ones—classic PAT behavior where many internal hosts share a few public IPs. On the ENCOR 350-401 exam, interpreting NAT statistics output tests your ability to distinguish between static NAT, dynamic NAT, and PAT by reading the "extended" flag and the "refcount" in the pool mapping. A common trap is assuming a pool with many addresses means no PAT is used, but the "extended" keyword overrides that assumption. Memory tip: if you see "extended," think "PAT—ports extend the translation."
CCNP NAT and DHCP Practice Question
This 350-401 practice question tests your understanding of nat and dhcp. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A network engineer runs the following command on Router R3:
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router is performing Port Address Translation (PAT).
The statistics show 5 active dynamic translations, all extended (PAT). The pool POOL1 has 10 addresses, but only 5 are currently used. The misses indicate packets that triggered new translations.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The NAT pool has exhausted all available addresses.
Why it's wrong here
Only 5 of 10 addresses are used, so the pool is not exhausted.
✗
The NAT translations are all static.
Why it's wrong here
The output shows 0 static and 5 dynamic translations.
✓
The router is performing Port Address Translation (PAT).
Why this is correct
The translations are 'extended', which indicates PAT is being used.
The inside interface is GigabitEthernet0/1; outside is GigabitEthernet0/0.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Command / output trap
The output shows 0 static and 5 dynamic translations.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 350-401 subnetting questions on CIDR, address ranges, and subnet selection.
NAT and DHCP — This question tests NAT and DHCP — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The router is performing Port Address Translation (PAT). — The statistics show 5 active dynamic translations, all extended (PAT). The pool POOL1 has 10 addresses, but only 5 are currently used. The misses indicate packets that triggered new translations.
What should I do if I get this 350-401 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 350-401 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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