Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A user reports that websites can be opened by IP address but not by hostname. Which service is the strongest suspect?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
DNS
This is correct because DNS is responsible for hostname resolution.
B
Distractor review
STP
This is wrong because spanning tree does not resolve hostnames.
C
Distractor review
PAT
This is wrong because NAT issues would more often affect IP connectivity itself, not just name resolution.
D
Distractor review
Port security
This is wrong because port security does not provide hostname lookup.
Common exam trap
Common exam trap: answer the scenario, not the keyword
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.
Technical deep dive
How to think about this question
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.
KKey Concepts to Remember
- DNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name.
- If a user can reach a website by IP address but not hostname, DNS is the primary service to verify for resolution issues.
- Cisco devices use DNS settings configured on clients and routers to perform hostname-to-IP address resolution.
- PAT affects IP address translation but does not impact the DNS process or hostname resolution directly.
- STP prevents Layer 2 loops and does not participate in IP layer name resolution or DNS functionality.
- Port security controls switch port access but does not influence DNS or hostname resolution processes.
- Troubleshooting DNS issues requires verifying DNS server reachability, client DNS configuration, and network ACLs affecting DNS traffic.
- Successful IP connectivity with hostname resolution failure strongly indicates DNS misconfiguration or service failure.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
DNS translates human-friendly hostnames into IP addresses, enabling users to access network resources by name.
What is the correct answer to this question?
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.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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