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 human-friendly hostnames into IP addresses, enabling users to access network resources by name.. 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 user reports that websites can be opened by IP address but not by hostname. Which service is the strongest suspect?
DNS
This is correct because DNS is responsible for hostname resolution.
STP
Why wrong: This is wrong because spanning tree does not resolve hostnames.
PAT
Why wrong: This is wrong because NAT issues would more often affect IP connectivity itself, not just name resolution.
Port security
Why wrong: This is wrong because port security does not provide hostname lookup.
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
DNS is the strongest suspect because the network path clearly works at the IP layer. In practical terms, if the user can reach the site by numeric address, then routing and basic connectivity are functioning. The missing piece is name resolution, and that is exactly what DNS provides. This is one of the clearest troubleshooting patterns in networking. If names fail but IP works, start with DNS.
Key principle: DNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
DNS
STP
Why it's wrong here
This is wrong because spanning tree does not resolve hostnames.
When this WOULD be correct
If the question were about a network topology where a loop is causing broadcast storms and preventing devices from communicating properly, a question could ask which protocol is responsible for maintaining a loop-free environment. In that case, STP would be the correct answer.
PAT
Why it's wrong here
This is wrong because NAT issues would more often affect IP connectivity itself, not just name resolution.
When this WOULD be correct
If the question were to ask about a scenario where users can access services using IP addresses but not through specific port numbers due to address translation issues, PAT would be the correct answer. For example, if a user can connect to a web server using its IP but cannot access it via a specific service port due to misconfigured PAT rules.
Port security
Why it's wrong here
This is wrong because port security does not provide hostname lookup.
When this WOULD be correct
If the question were about a network where users were unable to connect to devices on the network due to unauthorized MAC addresses being blocked by port security, then port security would be the correct answer. In this scenario, the inability to access devices would be due to port security settings.
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
This is correct because DNS is responsible for hostname resolution.
Why this is wrong here
STP (Spanning Tree Protocol) is a network protocol used to prevent loops in Ethernet networks. It does not resolve hostnames to IP addresses, making it irrelevant to the issue of accessing websites by hostname.
★ When this WOULD be the correct answer
If the question were about a network topology where a loop is causing broadcast storms and preventing devices from communicating properly, a question could ask which protocol is responsible for maintaining a loop-free environment. In that case, STP would be the correct answer.
Why candidates choose this
Candidates may confuse STP with other network services and protocols, leading them to mistakenly believe it could be related to hostname resolution issues due to its role in network stability.
Why this is wrong here
PAT (Port Address Translation) is used for translating private IP addresses to a public IP address, but it does not affect hostname resolution. The issue described in the question is related to DNS, which resolves hostnames to IP addresses.
★ When this WOULD be the correct answer
If the question were to ask about a scenario where users can access services using IP addresses but not through specific port numbers due to address translation issues, PAT would be the correct answer. For example, if a user can connect to a web server using its IP but cannot access it via a specific service port due to misconfigured PAT rules.
Why candidates choose this
Candidates may confuse PAT with DNS issues, thinking that if IP addresses work, there might be a translation issue affecting port access, leading them to choose this option mistakenly.
Why this is wrong here
Port security is a feature used to restrict access to a switch port based on MAC addresses, and it does not directly affect the resolution of hostnames to IP addresses. Therefore, it cannot be the cause of the issue where websites are accessible by IP but not by hostname.
★ When this WOULD be the correct answer
If the question were about a network where users were unable to connect to devices on the network due to unauthorized MAC addresses being blocked by port security, then port security would be the correct answer. In this scenario, the inability to access devices would be due to port security settings.
Why candidates choose this
Candidates may choose this option if they associate network access issues with security measures, mistakenly believing that port security could impact hostname resolution due to its role in controlling device access on the network.
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 PAT or port security as the cause of hostname resolution failure. PAT manages IP address translation for outbound connections but does not resolve hostnames, so it cannot cause DNS failures. Similarly, port security restricts switch port access based on MAC addresses and does not affect DNS or name resolution. Another tempting but incorrect choice is STP, which operates at Layer 2 to prevent loops and has no role in IP name resolution. Candidates must avoid confusing these distinct network services and focus on DNS when hostname resolution fails but IP connectivity works.
Detailed technical explanation
Domain Name System (DNS) is a critical IP service that translates human-readable hostnames into IP addresses, enabling users to access websites and network resources by name rather than numeric IP. DNS operates through a hierarchical distributed database, where DNS servers respond to queries by resolving domain names to their corresponding IP addresses. In Cisco networking and the CCNA context, DNS is essential for name resolution in both enterprise and service provider environments, facilitating seamless connectivity and user-friendly access. When a user can access websites by IP address but not by hostname, the issue typically lies in the DNS resolution process. This indicates that the underlying IP routing and connectivity are functioning correctly, but the DNS service is either misconfigured, unreachable, or failing to resolve names. Troubleshooting this involves verifying DNS server settings on the client and network devices, ensuring DNS services are operational, and checking for any ACLs or firewall rules blocking DNS traffic (usually UDP/TCP port 53). A common exam trap is confusing DNS issues with other network services like NAT or STP. For example, PAT (Port Address Translation) affects IP address translation but does not impact hostname resolution directly. Similarly, STP (Spanning Tree Protocol) manages Layer 2 loop prevention and does not influence DNS or name resolution. Understanding the distinct roles of these services prevents misdiagnosis. Practically, network engineers must isolate DNS problems by confirming IP connectivity first, then focusing on DNS configurations and server availability to resolve hostname resolution failures.
Key takeaway
DNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name.
Real-world example
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
Review dNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Services and Security — study guide chapter
Learn the concepts, then practise the questions
Network Services and Security practice questions
Targeted practice on this topic area only
All 200-301 questions
1,819 questions across all exam domains
CCNA 200-301 v2 study guide
Full concept coverage aligned to exam objectives
200-301 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise 200-301 questions linked to Network Infrastructure and Connectivity.
Practise 200-301 questions linked to Switching and Network Access.
Practise 200-301 questions linked to IP Routing.
Practise 200-301 questions linked to Network Services and Security.
Practise 200-301 questions linked to AI and Network Operations.
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Network Services and Security — This question tests Network Services and Security — DNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name..
The correct answer is: DNS — DNS is the strongest suspect because the network path clearly works at the IP layer. In practical terms, if the user can reach the site by numeric address, then routing and basic connectivity are functioning. The missing piece is name resolution, and that is exactly what DNS provides. This is one of the clearest troubleshooting patterns in networking. If names fail but IP works, start with DNS.
Review dNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name., then practise related 200-301 questions on the same topic to reinforce the concept.
DNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name.
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 →
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.