The answer is that the DNS server lacks a host record for the internal website. This is the most likely cause because when employees type the website’s hostname, their computers send a DNS query to resolve that name into an IP address; without a corresponding host record in the DNS zone, the query fails, and the browser cannot reach the server at 192.168.1.10. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of how internal DNS resolution differs from internet access—a common trap is assuming that internet connectivity guarantees local name resolution, but DHCP only provides IP configuration, not DNS records for private resources. Remember that a host record (an A record for IPv4) explicitly maps a hostname to a private IP, so if internal sites are unreachable by name but the internet works, always check the DNS server first. A helpful memory tip is “No A record, no arrival”—without that host record, the name simply cannot be found.
220-1101 Network Services Practice Question
This 220-1201 practice question tests your understanding of network services. 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 small business reports that employees can access the internet but cannot reach the internal company website hosted on a local server. The server's IP address is 192.168.1.10, and clients use DHCP. What is the most likely cause?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The DNS server lacks a host record for the internal website.
This question tests understanding of DNS resolution for internal resources. When a server hosts an internal website, clients need a DNS record (often a host record) to resolve its hostname to the private IP address. Without it, clients can't reach the site by name even with internet access.
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 DHCP server is not assigning the correct subnet mask.
Why it's wrong here
Incorrect subnet mask would affect all network communication, not just internal website access.
✓
The DNS server lacks a host record for the internal website.
Why this is correct
A missing A or host record prevents name resolution for the internal site, while internet DNS works fine.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
The switch port connecting the server is administratively down.
Why it's wrong here
If the switch port were down, the server would be unreachable entirely, not just via hostname.
✗
The firewall is blocking port 443 inbound.
Why it's wrong here
Blocking port 443 would affect HTTPS access but not explain why employees can't reach the site by name while having internet.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
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.
Network Services — This question tests Network Services — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The DNS server lacks a host record for the internal website. — This question tests understanding of DNS resolution for internal resources. When a server hosts an internal website, clients need a DNS record (often a host record) to resolve its hostname to the private IP address. Without it, clients can't reach the site by name even with internet access.
What should I do if I get this 220-1201 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 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is troubleshooting a network where users can access the internet but cannot connect to a specific internal application server by its hostname. Pinging the server's IP address works. The DNS server is configured correctly for external names. What is the most likely cause?
medium
A.The DHCP server is out of IP addresses
✓ B.The DNS server does not have an A record for the application server
C.NAT is misconfigured for the internal network
D.The proxy server is blocking the hostname
Why B: The DNS server resolves external names but not the internal hostname, indicating a missing or incorrect DNS record (A or CNAME) for the internal server. DHCP is not involved, and NAT is working since internet access is fine. A proxy server could interfere but is less likely than a missing DNS record.
Variation 2. A company's internal website is accessible by IP address but not by its hostname. The website is hosted on a server with a static IP. Which service is most likely misconfigured?
medium
A.DHCP
B.NAT
✓ C.DNS
D.RADIUS
Why C: This question tests DNS resolution for internal resources. Access by IP works, so the server is reachable. The problem is name resolution, which points to a missing or incorrect DNS record for that hostname.
Last reviewed: Jun 18, 2026
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