- A
The DHCP server is out of IP addresses
Why wrong: DHCP exhaustion would prevent new devices from getting IPs, but users already have IPs and can access the internet.
- B
The DNS server does not have an A record for the application server
Without an A record, DNS cannot resolve the hostname to the server's IP, even though the server is reachable by IP.
- C
NAT is misconfigured for the internal network
Why wrong: NAT is used for external traffic; internal traffic typically does not go through NAT, and internet access works.
- D
The proxy server is blocking the hostname
Why wrong: A proxy could block hostnames, but the more common and direct cause is a missing DNS record.
Question 714 of 1,020
220-1201 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 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?
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 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
✓
The DNS server does not have an A record for the application server
Since users can access the internet and ping the server by IP, the network connectivity and external DNS resolution are working. The failure to resolve the internal server's hostname indicates that the DNS server lacks an A record for that specific hostname, preventing name-to-IP resolution for internal resources.
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.
- ✗
The DHCP server is out of IP addresses
- ✓
The DNS server does not have an A record for the application server
Why this is correct
Without an A record, DNS cannot resolve the hostname to the server's IP, even though the server is reachable by IP.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
NAT is misconfigured for the internal network
Why it's wrong here
NAT is used for external traffic; internal traffic typically does not go through NAT, and internet access works.
- ✗
The proxy server is blocking the hostname
Why it's wrong here
A proxy could block hostnames, but the more common and direct cause is a missing DNS record.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between connectivity issues (IP reachable) and name resolution issues (hostname unreachable) to trap candidates into misdiagnosing DNS problems as routing or NAT failures.
Detailed technical explanation
How to think about this question
DNS A records map a hostname to an IPv4 address. When a client queries the DNS server for an internal hostname, the server must have a corresponding A record in its forward lookup zone. Without it, the query returns an NXDOMAIN or no answer, causing the connection to fail by name. Tools like `nslookup` or `dig` can confirm whether the record exists; a successful ping to the IP bypasses DNS entirely.
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
Quick reference
Common DNS Record Types
| Record | Purpose | Example |
|---|---|---|
| A | IPv4 address mapping | example.com → 93.184.216.34 |
| AAAA | IPv6 address mapping | example.com → 2606:2800::1 |
| CNAME | Alias to another hostname | www → example.com |
| MX | Mail server for domain | example.com → mail.example.com (priority 10) |
| TXT | Text data (SPF, DKIM, verification) | v=spf1 include:_spf.example.com ~all |
| NS | Authoritative name servers | example.com NS ns1.example.com |
| PTR | Reverse DNS (IP → hostname) | 34.216.184.93.in-addr.arpa → example.com |
| SOA | Zone authority record | Primary NS, admin email, serial, TTL defaults |
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Network Services — This question tests Network Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The DNS server does not have an A record for the application server — Since users can access the internet and ping the server by IP, the network connectivity and external DNS resolution are working. The failure to resolve the internal server's hostname indicates that the DNS server lacks an A record for that specific hostname, preventing name-to-IP resolution for internal resources.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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