CCNA Network Services and Security Practice Question
Users can reach a server by IP address but not by hostname. Which service should be checked first?
⚠ Common exam trap
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.
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
✓
DNS
If the server is reachable by IP but not by name, the likely issue is name resolution, which points to DNS.
Answer analysis
Option-by-option breakdown
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 (Network Time Protocol) synchronizes clocks across network devices. It does not participate in hostname-to-IP address translation. Even if NTP were misconfigured or unreachable, a user could still resolve and reach a server by hostname; therefore it cannot be the cause of a DNS-style failure where IP access succeeds but name-based access fails.
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
Why this is correct
Users can reach a server by IP address but not by hostname. This is the classic symptom of a DNS resolution failure: the client cannot translate the fully qualified domain name (FQDN) into an IP address, so the connection attempt fails at the name lookup stage. The fact that the IP path itself works proves Layer 3 routing and the server's services are reachable, isolating the problem to name resolution.
- ✗
QoS
Why it's wrong here
QoS (Quality of Service) manages network traffic prioritization and bandwidth guarantees. It operates on packets already addressed and forwarded through the network. A QoS misconfiguration might cause drops or latency, but it would not block the conversion of a hostname to an IP address, nor would it produce a symptom where the IP works but the name does not.
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
HSRP (Hot Standby Router Protocol) provides first-hop router redundancy using a virtual IP and MAC address. If HSRP were misbehaving, the symptom would typically be intermittent or total loss of connectivity to the default gateway, affecting all traffic equally — including IP-based access. The fact that IP access works fine rules out gateway redundancy issues.
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
Why each answer is right or wrong
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.
✓DNSCorrect answer▾
Why this is correct
Users can reach a server by IP address but not by hostname. This is the classic symptom of a DNS resolution failure: the client cannot translate the fully qualified domain name (FQDN) into an IP address, so the connection attempt fails at the name lookup stage. The fact that the IP path itself works proves Layer 3 routing and the server's services are reachable, isolating the problem to name resolution.
✗NTPWrong answer — click to see why▾
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.
✗QoSWrong answer — click to see why▾
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.
✗HSRPWrong answer — click to see why▾
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?”
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 |
Go deeper
Related to this question
Learn chapter
RA Guard — IPv6 First-Hop Security
Key term
DNS
DNS is the system that translates human-friendly domain names like example.com into machine-readable IP addresses so computers can find each other on a network.
Key term
IP address
An IP address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.