This 200-301 practice question tests your understanding of network services and security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: dNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs.. 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.
Users can reach a server by IP address but not by hostname. Which service should be checked first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
NTP
Why wrong: NTP handles time synchronization, not hostname resolution.
DNS
Correct. This symptom strongly suggests a DNS issue.
QoS
Why wrong: QoS is unrelated to name resolution.
HSRP
Why wrong: Gateway redundancy is not the primary issue here.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
DNS
If the server is reachable by IP but not by name, the likely issue is name resolution, which points to DNS.
Key principle: DNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
NTP
Why it's wrong here
NTP handles time synchronization, not hostname resolution.
When this WOULD be correct
If the exam question asked about issues related to time synchronization affecting application performance that relies on timestamps, NTP could be the correct answer. For example, if users are experiencing problems with logging or data integrity due to time discrepancies, NTP would be the service to check.
DNS
QoS
Why it's wrong here
QoS is unrelated to name resolution.
When this WOULD be correct
In a scenario where a question asks about troubleshooting network performance issues related to bandwidth allocation or latency, QoS would be the correct service to check first. For instance, if users report slow access to a server by both IP and hostname, indicating potential traffic shaping issues.
HSRP
Why it's wrong here
Gateway redundancy is not the primary issue here.
When this WOULD be correct
In a scenario where the question asks about ensuring high availability and failover for multiple routers in a network, HSRP would be the correct answer. For example, if users are unable to reach a server due to a router failure, checking HSRP configurations would be appropriate.
Option-by-option analysis
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
Why this is correct
Correct. This symptom strongly suggests a DNS issue.
Why this is wrong here
NTP (Network Time Protocol) is used for synchronizing clocks between devices, not for resolving hostnames to IP addresses. A DNS issue would cause the described symptom, not an NTP issue.
★ When this WOULD be the correct answer
If the exam question asked about issues related to time synchronization affecting application performance that relies on timestamps, NTP could be the correct answer. For example, if users are experiencing problems with logging or data integrity due to time discrepancies, NTP would be the service to check.
Why candidates choose this
Students might confuse NTP with DNS because both are network services, or they might think time synchronization is needed for hostname resolution, but that is incorrect.
Why this is wrong here
QoS (Quality of Service) manages network traffic prioritization and bandwidth allocation, not name resolution. It would not affect the ability to reach a server by hostname.
★ When this WOULD be the correct answer
In a scenario where a question asks about troubleshooting network performance issues related to bandwidth allocation or latency, QoS would be the correct service to check first. For instance, if users report slow access to a server by both IP and hostname, indicating potential traffic shaping issues.
Why candidates choose this
Students might think QoS could block or delay DNS traffic, but the symptom is specific to hostname resolution, not performance. QoS issues would typically cause poor performance, not complete failure to resolve.
Why this is wrong here
HSRP (Hot Standby Router Protocol) provides first-hop redundancy for default gateways, not hostname resolution. A gateway issue would prevent all IP communication, not just hostname-based access.
★ When this WOULD be the correct answer
In a scenario where the question asks about ensuring high availability and failover for multiple routers in a network, HSRP would be the correct answer. For example, if users are unable to reach a server due to a router failure, checking HSRP configurations would be appropriate.
Why candidates choose this
Students might confuse HSRP with DNS because both involve redundancy or failover, but HSRP is unrelated to name resolution. The symptom of being able to reach by IP but not hostname points to DNS, not gateway redundancy.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
A common exam trap is selecting NTP, QoS, or HSRP as the cause when users cannot reach a server by hostname. NTP synchronizes time and does not affect name resolution. QoS prioritizes traffic but does not translate hostnames to IP addresses. HSRP provides gateway redundancy and does not influence DNS functionality. Choosing any of these distractors wastes time and leads to incorrect troubleshooting. The key is to recognize that hostname resolution depends solely on DNS, so DNS must be the first service checked when IP connectivity exists but hostname access fails.
Detailed technical explanation
Domain Name System (DNS) is a critical IP service that translates human-readable hostnames into IP addresses, enabling users and devices to locate servers and resources on a network. Without DNS, users must know the exact IP address to reach a server, which is impractical in dynamic or large networks. Cisco devices rely on DNS to resolve names for management, troubleshooting, and application access, making DNS a foundational service in IP networking. When users can reach a server by IP address but not by hostname, the issue typically lies in DNS resolution failure. This means the client device or network device cannot translate the hostname into the corresponding IP address. Troubleshooting involves verifying DNS server configuration, ensuring the DNS server is reachable, and confirming that the DNS records for the hostname exist and are correct. Cisco IOS commands like 'show hosts' and 'ping' by hostname help diagnose DNS issues. A common exam trap is confusing DNS with other IP services like NTP, QoS, or HSRP, which do not handle hostname resolution. For example, NTP synchronizes time, QoS manages traffic priority, and HSRP provides gateway redundancy. Misidentifying the service leads to wasted troubleshooting effort. Practically, ensuring DNS is operational and correctly configured is essential for network usability and name-based communication, especially in enterprise environments where hostnames are preferred over IP addresses.
Key takeaway
DNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs.
Real-world example
A practitioner preparing for the 200-301 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. DNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Review dNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Network Services and Security — This question tests Network Services and Security — DNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs..
The correct answer is: DNS — If the server is reachable by IP but not by name, the likely issue is name resolution, which points to DNS.
Review dNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs., then practise related 200-301 questions on the same topic to reinforce the concept.
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
DNS translates hostnames into IP addresses, enabling users to access servers without memorizing numeric IPs.
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Last reviewed: May 17, 2026
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.
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