Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A user can reach a remote web server by IP address but not by hostname. Which service should be checked first?
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 resolving hostnames into IP information.
B
Distractor review
STP
This is wrong because spanning-tree does not provide hostname resolution.
C
Distractor review
PAT
This is wrong because NAT issues would typically affect IP connectivity more broadly, not just name resolution.
D
Distractor review
Port security
This is wrong because port security does not resolve hostnames.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting PAT or STP as the cause when a user cannot reach a server by hostname but can by IP address. Candidates may mistakenly associate PAT with all IP-related issues, but PAT only translates IP addresses and ports for outbound traffic and does not resolve hostnames. Similarly, STP manages Layer 2 loop prevention and does not affect Layer 3 name resolution. Confusing these services with DNS leads to incorrect troubleshooting steps. The key is to recognize that DNS is the only service responsible for translating hostnames to IP addresses, so it must be checked first when name resolution fails but IP connectivity succeeds.
Technical deep dive
How to think about this question
The Domain Name System (DNS) is a fundamental IP service that translates human-readable hostnames into IP addresses, enabling users and applications to locate resources on a network or the internet. When a user enters a hostname, the DNS client queries a DNS server to resolve that name into its corresponding IP address. This process is essential because network communication relies on IP addresses, not hostnames. Cisco devices and networks depend heavily on DNS for name resolution, especially in environments where users or systems access resources by name rather than by numeric IP. In troubleshooting connectivity issues where a user can reach a remote server by IP address but not by hostname, the first step is to verify the DNS service. This is because successful IP connectivity confirms that routing and switching functions are operational, and the problem lies specifically in the name resolution process. Cisco IOS devices use DNS settings configured via commands such as 'ip name-server' to specify DNS servers. If DNS is misconfigured, unreachable, or the DNS server lacks the correct records, hostname resolution will fail, causing access issues despite valid IP connectivity. A common exam trap is to confuse DNS issues with other network services like NAT or spanning-tree. 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. Understanding that DNS operates at the application layer and is responsible solely for name-to-IP mapping helps avoid misdiagnosis. In practical Cisco networking, ensuring DNS servers are reachable and correctly configured is critical for seamless hostname-based access.
KKey Concepts to Remember
- DNS translates human-readable hostnames into IP addresses, enabling network devices to locate resources using names instead of numeric IPs.
- A user reaching a server by IP but not hostname indicates a failure in the DNS name resolution process rather than routing or switching.
- Cisco devices use the 'ip name-server' command to configure DNS servers for hostname resolution within the network.
- PAT affects IP address translation for outbound connections but does not influence DNS or hostname resolution.
- STP prevents Layer 2 network loops and does not participate in resolving hostnames or IP addresses.
- Port security controls switch port access based on MAC addresses and does not impact DNS or name resolution.
- When IP connectivity works but hostname resolution fails, DNS is the primary service to verify first in Cisco network troubleshooting.
- Misconfiguring DNS settings or unreachable DNS servers commonly cause hostname resolution failures despite valid IP connectivity.
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-readable hostnames into IP addresses, enabling network devices to locate resources using names instead of numeric IPs.
What is the correct answer to this question?
The correct answer is: DNS — DNS should be checked first. In plain language, the path to the server appears to work because the user can reach it by numeric address. The missing function is the translation from hostname to IP-related information, and that is exactly what DNS provides. This is one of the clearest service-troubleshooting patterns in networking. If IP works but the name fails, DNS becomes the strongest first suspect. The correct answer is therefore the name-resolution service rather than a routing or switching feature.
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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