Question 735 of 2,152
NAT and PATmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is that inside hosts are dynamically mapped one-to-one to a pool address, and if the pool is exhausted, new translations fail. This is the effect of dynamic NAT without overload, also known as dynamic one-to-one translation, where the `ip nat inside source list 1 pool MYPOOL` command binds each inside host to a unique public address from the pool without port address translation (PAT). On the Cisco CCNP ENARSI 300-410 exam, this configuration tests your understanding of how dynamic NAT differs from PAT—a common trap is assuming overload is enabled by default, but here the absence of the `overload` keyword means no port multiplexing occurs. When the pool of five addresses (203.0.113.10 through 203.0.113.20) is fully allocated, any additional inside host attempting outbound communication will simply fail to translate. Memory tip: think “no overload, no sharing”—each inside host gets its own public IP, and once the pool is empty, new connections are dropped.

300-410 NAT and PAT Practice Question

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 partial configuration:

ip nat pool MYPOOL 203.0.113.10 203.0.113.20 netmask 255.255.255.0
ip nat inside source list 1 pool MYPOOL
access-list 1 permit 192.168.1.0 0.0.0.255

What is the effect?

Question 1mediummultiple choice
Read the full NAT/PAT explanation →

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 are dynamically mapped to a pool address; if the pool is exhausted, new translations fail.

This configures dynamic NAT without overload, so translations are one-to-one from inside addresses to the pool. If more inside hosts than pool addresses try to communicate, some will fail.

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.

  • Inside hosts are translated to addresses in the pool using PAT.

    Why it's wrong here

    No 'overload' keyword means no port multiplexing; it's one-to-one dynamic NAT.

  • Inside hosts are dynamically mapped to a pool address; if the pool is exhausted, new translations fail.

    Why this is correct

    Without overload, each translation consumes one pool address; exhaustion blocks new flows.

    Related concept

    CIDR notation defines the prefix length.

  • The router uses the pool address as the source for all outbound traffic, regardless of ACL.

    Why it's wrong here

    The ACL restricts which inside addresses are eligible for translation.

  • This configuration requires the 'ip nat outside' interface command to function.

    Why it's wrong here

    While 'ip nat outside' is needed on the outside interface, the question asks about the effect of the given commands alone; the effect is dynamic NAT without overload.

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

  • Keyword trap

    No 'overload' keyword means no port multiplexing; it's one-to-one dynamic NAT.

  • Command / output trap

    While 'ip nat outside' is needed on the outside interface, the question asks about the effect of the given commands alone; the effect is dynamic NAT without overload.

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 300-410 subnetting questions on CIDR, address ranges, and subnet selection.

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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 — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: Inside hosts are dynamically mapped to a pool address; if the pool is exhausted, new translations fail. — This configures dynamic NAT without overload, so translations are one-to-one from inside addresses to the pool. If more inside hosts than pool addresses try to communicate, some will fail.

What should I do if I get this 300-410 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 300-410 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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Last reviewed: Jun 19, 2026

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