Question 571 of 1,020

Network Configuration Concepts →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that NAT is not enabled for the guest subnet. This is correct because the access point can ping the router’s guest interface at 192.168.2.1, proving Layer 3 connectivity is working, but it cannot reach the internet. Without Network Address Translation (NAT) on the 192.168.2.0/24 subnet, the router will forward guest traffic to the ISP modem using private IP addresses, which the modem cannot route back—it has no route to 192.168.2.x. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding that NAT is required for private IP ranges to access public networks; a common trap is assuming a default route alone is sufficient. The employee subnet works because NAT is likely already configured for 192.168.1.0/24. Memory tip: think “NAT for the net”—if a subnet can’t reach the internet, check that NAT is enabled for that specific subnet, not just the router’s WAN interface.

220-1201 Network Configuration Concepts Practice Question

This 220-1201 practice question tests your understanding of network configuration concepts. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 administrator is configuring a small business network with two subnets: 192.168.1.0/24 for employees and 192.168.2.0/24 for guests. The router has two LAN interfaces with IPs 192.168.1.1 and 192.168.2.1. A technician connects a new access point to the guest subnet switch and configures it with a static IP of 192.168.2.50. The access point can ping the router's guest interface but cannot reach the internet. The router's default route points to an ISP modem at 203.0.113.1. What is the most likely missing configuration?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Review the full subnetting walkthrough →

A
The access point's default gateway is set to 192.168.1.1.
Why wrong: If the gateway were set to the employee subnet, the access point would not be able to ping the router's guest interface (192.168.2.1), but it can, so the gateway is likely correct.
B
NAT is not enabled for the 192.168.2.0/24 subnet on the router.
Without NAT, the router will not translate private IPs from the guest subnet to the public IP, so traffic cannot reach the internet. The employee subnet works because NAT is likely enabled for it.
C
The access point has a duplicate IP address.
Why wrong: A duplicate IP would cause conflicts, but the access point can ping the router, so the IP is likely unique.
D
The ISP modem is blocking traffic from the guest subnet.
Why wrong: The ISP modem typically routes based on the router's public IP, not private subnets. The issue is on the router, not the modem.

Full breakdown with real-world context →

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

✓

NAT is not enabled for the 192.168.2.0/24 subnet on the router.

The access point can reach the router's guest interface, but not the internet. This suggests the router is not performing NAT for the guest subnet, or the router lacks a route back from the ISP modem. Typically, for internet access, the router must have NAT enabled for the guest subnet, and the ISP modem must have a route back to the guest subnet. Since the employee subnet works, the router likely has NAT for 192.168.1.0/24 but not for 192.168.2.0/24.

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 access point's default gateway is set to 192.168.1.1.
Why it's wrong here
If the gateway were set to the employee subnet, the access point would not be able to ping the router's guest interface (192.168.2.1), but it can, so the gateway is likely correct.
✓
NAT is not enabled for the 192.168.2.0/24 subnet on the router.
Why this is correct
Without NAT, the router will not translate private IPs from the guest subnet to the public IP, so traffic cannot reach the internet. The employee subnet works because NAT is likely enabled for it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
CIDR notation defines the prefix length.
✗
The access point has a duplicate IP address.
Why it's wrong here
A duplicate IP would cause conflicts, but the access point can ping the router, so the IP is likely unique.
✗
The ISP modem is blocking traffic from the guest subnet.
Why it's wrong here
The ISP modem typically routes based on the router's public IP, not private subnets. The issue is on the router, not the modem.

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.

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 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.

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FAQ

Questions learners often ask

What does this 220-1201 question test?

Network Configuration Concepts — This question tests Network Configuration Concepts — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: NAT is not enabled for the 192.168.2.0/24 subnet on the router. — The access point can reach the router's guest interface, but not the internet. This suggests the router is not performing NAT for the guest subnet, or the router lacks a route back from the ISP modem. Typically, for internet access, the router must have NAT enabled for the guest subnet, and the ISP modem must have a route back to the guest subnet. Since the employee subnet works, the router likely has NAT for 192.168.1.0/24 but not for 192.168.2.0/24.

What should I do if I get this 220-1201 question wrong?

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

CIDR notation defines the prefix length.

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