- A
High CPU utilization on a router
High CPU utilization on a router typically indicates that the device is struggling to process packets or control plane traffic, which is an infrastructure issue. This observation points to the need for infrastructure service area review.
- B
CRC errors on an interface
Why wrong: CRC errors indicate physical layer problems such as faulty cabling, interference, or hardware issues. They do not point to infrastructure service area but rather to physical layer issues.
- C
Authentication failures in logs
Why wrong: Authentication failures are security-related events, not infrastructure issues. They indicate potential unauthorized access attempts or misconfigurations in security policies.
- D
High latency on a link
Why wrong: High latency typically points to transport layer issues or network congestion, not infrastructure. It may be caused by distance, queuing delays, or bandwidth constraints.
CCNA Network Services and Security Practice Question
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 resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works.. 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.
Match each observation to the service area it most strongly suggests 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.
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
High CPU utilization on a router
The given observations directly map to network services: 'Application works by IP but not by name' indicates the host can reach the destination but cannot resolve its name to an IP address, pointing to a DNS issue. 'Host does not receive IP settings automatically' means the DHCP process failed, so the host cannot obtain an IP address automatically, implicating the DHCP service. 'Device logs show inconsistent timestamps' reveals that time synchronization is broken, which is the role of NTP. Finally, 'Operations team cannot review centralized event messages' suggests that logging messages are not being sent to a central server, indicating a problem with the syslog service.
Key principle: DNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
High CPU utilization on a router
Why this is correct
High CPU utilization on a router typically indicates that the device is struggling to process packets or control plane traffic, which is an infrastructure issue. This observation points to the need for infrastructure service area review.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
DNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works.
- ✗
CRC errors on an interface
Why it's wrong here
CRC errors indicate physical layer problems such as faulty cabling, interference, or hardware issues. They do not point to infrastructure service area but rather to physical layer issues.
- ✗
Authentication failures in logs
Why it's wrong here
Authentication failures are security-related events, not infrastructure issues. They indicate potential unauthorized access attempts or misconfigurations in security policies.
- ✗
High latency on a link
Why it's wrong here
High latency typically points to transport layer issues or network congestion, not infrastructure. It may be caused by distance, queuing delays, or bandwidth constraints.
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.
✓High CPU utilization on a routerCorrect answer▾
Why this is correct
High CPU utilization on a router typically indicates that the device is struggling to process packets or control plane traffic, which is an infrastructure issue. This observation points to the need for infrastructure service area review.
✗CRC errors on an interfaceWrong answer — click to see why▾
Why this is wrong here
CRC errors are layer 1 issues, not infrastructure (which typically involves device-level resources like CPU/memory).
Why candidates choose this
Candidates might associate any error with infrastructure, but CRC errors are specifically physical layer.
✗Authentication failures in logsWrong answer — click to see why▾
Why this is wrong here
Authentication failures belong to the security domain, not infrastructure.
Why candidates choose this
Candidates might think authentication failures indicate a problem with the device's infrastructure, but they are security events.
✗High latency on a linkWrong answer — click to see why▾
Why this is wrong here
High latency is a performance metric related to transport or network layers, not device infrastructure.
Why candidates choose this
Candidates might associate high latency with device overload (infrastructure), but latency is more about path and congestion.
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
Common exam trap: answer the scenario, not the keyword
Do not confuse service functions: DNS resolves names to IPs, not IP assignment; DHCP provides automatic IP assignment, not name resolution; NTP synchronizes time, not event logs; syslog centralizes event messages, not time synchronization.
Detailed technical explanation
How to think about this question
DNS (Domain Name System) is a critical IP service that translates human-readable hostnames into IP addresses. In Cisco networks, when hostname access fails but IP connectivity is intact, the issue usually lies with DNS resolution. Cisco devices rely on DNS to resolve names for management and routing protocols. Troubleshooting DNS involves verifying DNS server IPs, domain names, and name resolution commands such as 'nslookup' or 'ping' with hostnames. DHCP (Dynamic Host Configuration Protocol) automates IP address assignment to hosts. When automatic addressing fails, devices cannot obtain IP addresses, leading to connectivity loss. Cisco routers and switches can act as DHCP servers or relay agents. Troubleshooting DHCP issues involves checking DHCP pools, scopes, lease availability, and relay configurations. DHCP failures are distinct from DNS because they prevent IP assignment rather than name resolution. NTP (Network Time Protocol) synchronizes clocks across network devices, ensuring consistent timestamps in logs and events. If event timelines disagree, it indicates NTP misconfiguration or failure. Cisco devices use NTP to maintain accurate time, which is vital for troubleshooting and security auditing. Syslog centralizes event logging from multiple devices. Lack of centralized Syslog visibility hinders event correlation and fault isolation. Proper Syslog configuration involves setting server IPs, severity levels, and transport protocols. Understanding these IP services and their symptoms enables precise fault domain identification in Cisco networks.
KKey Concepts to Remember
- DNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works.
- DHCP assigns IP addresses dynamically and should be the focus when devices fail to obtain automatic addressing.
- NTP synchronizes device clocks to ensure consistent event timestamps, critical when event timelines disagree.
- Syslog centralizes event logging from multiple devices, enabling centralized visibility and easier troubleshooting.
- Good troubleshooting maps symptoms to the most relevant IP service domain to isolate faults efficiently in Cisco networks.
- Cisco devices rely on DNS for hostname resolution in routing and management protocols, making DNS critical for name-based access.
- DHCP failures prevent IP address assignment, which differs fundamentally from DNS resolution failures.
- NTP misconfiguration leads to inconsistent timestamps, complicating log analysis and event correlation.
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
DNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works.
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 dNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this 200-301 question test?
Network Services and Security — This question tests Network Services and Security — DNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works..
What is the correct answer to this question?
The correct answer is: High CPU utilization on a router — The given observations directly map to network services: 'Application works by IP but not by name' indicates the host can reach the destination but cannot resolve its name to an IP address, pointing to a DNS issue. 'Host does not receive IP settings automatically' means the DHCP process failed, so the host cannot obtain an IP address automatically, implicating the DHCP service. 'Device logs show inconsistent timestamps' reveals that time synchronization is broken, which is the role of NTP. Finally, 'Operations team cannot review centralized event messages' suggests that logging messages are not being sent to a central server, indicating a problem with the syslog service.
What should I do if I get this 200-301 question wrong?
Review dNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works., then practise related 200-301 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
DNS resolves hostnames to IP addresses and is the first service to check when hostname access fails but IP connectivity works.
About these practice questions
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Last reviewed: May 17, 2026
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