CCNA Network Services and Security Practice Question
Exhibit
PC1 ipconfig IPv4 Address . . . . . . . . . : 10.40.40.25 Subnet Mask . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . : 10.40.40.1 DNS Server . . . . . . . . . . : 10.4.4.4 PC1> ping 8.8.8.8 success PC1> ping www.example.com failed Correct internal DNS server: 10.40.10.53
Clients on a network can browse the internet by IP address but fail when using hostnames. What is the most likely problem?
⚠ Common exam trap
Cisco often tests the distinction between IP connectivity issues and name resolution issues, and the trap here is that candidates may incorrectly blame the default gateway or NAT when the symptom clearly isolates the problem to DNS.
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
✓
The client is using the wrong DNS server address.
The client can browse by IP address but not by hostname, which indicates that IP connectivity and routing are functional, but name resolution is failing. Since DNS translates hostnames to IP addresses, the most likely fault is that the client is configured with an incorrect DNS server address, preventing it from resolving domain names.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The default gateway on the PC is incorrect.
Why it's wrong here
If the default gateway on the PC were incorrect, the client could not successfully send packets to any off-subnet destination, including public IP addresses like 8.8.8.8. The fact that IP-based browsing works proves that the gateway is receiving, translating, and forwarding packets correctly. A default gateway problem would manifest as total internet failure, not as a DNS-only failure, so this option cannot explain the observed symptom.
When this WOULD be correct
In a different scenario where a question states that clients cannot access any external resources, including IP addresses, and the default gateway is incorrectly configured, this option would be correct. For example, if the question specifies that the clients are unable to communicate outside their local subnet, then an incorrect default gateway would be the cause.
- ✓
The client is using the wrong DNS server address.
Why this is correct
A misconfigured DNS server address causes the client to send name resolution queries to an endpoint that either cannot answer authoritatively or is completely unreachable. Since the client can already reach 8.8.8.8 by IP, the issue is specifically that the DNS resolver is not returning the A/AAAA record needed to translate the hostname. Verify the configured DNS server with ipconfig /all or nslookup, and correct it to a valid internal or public resolver such as 8.8.8.8.
- ✗
NAT overload is failing on the edge router.
Why it's wrong here
NAT overload (PAT) is what enables the client's private IP address to reach the public internet by translating source addresses and ports. Because the client successfully browsed to 8.8.8.8 by IP address, the NAT translation table entries must be valid and translation/return traffic must be working. If NAT overload were failing, even IP-based internet access would fail; therefore, this option is disproven by the very connectivity described in the prompt.
When this WOULD be correct
In a scenario where clients cannot access any external resources, including both IP addresses and hostnames, and the question specifies issues with NAT configurations, this option could be correct if the NAT overload configuration is misconfigured or overloaded.
- ✗
The switchport must be converted to a routed port.
Why it's wrong here
Converting a switchport to a routed port is a Layer 3 interface configuration used on multilayer switches for inter-VLAN routing or direct router connections, not for a regular host access port. DNS resolution is an application-layer process that uses UDP/TCP port 53 and is completely independent of whether the connected switchport is in Layer 2 or Layer 3 mode. Since the client already has IP connectivity, the switchport type is irrelevant to the DNS failure.
When this WOULD be correct
In a different scenario, if the question stated that clients are unable to communicate with devices on different subnets and the switchport configuration was incorrectly set to access mode instead of routed mode, this option would be correct. It would indicate that the switchport needs to be configured to allow routing between VLANs.
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.
✓The client is using the wrong DNS server address.Correct answer▾
Why this is correct
A misconfigured DNS server address causes the client to send name resolution queries to an endpoint that either cannot answer authoritatively or is completely unreachable. Since the client can already reach 8.8.8.8 by IP, the issue is specifically that the DNS resolver is not returning the A/AAAA record needed to translate the hostname. Verify the configured DNS server with ipconfig /all or nslookup, and correct it to a valid internal or public resolver such as 8.8.8.8.
✗The default gateway on the PC is incorrect.Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because if the default gateway on the PC were incorrect, the client would not be able to reach any external IP addresses, not just hostnames. The issue specifically pertains to DNS resolution, not routing.
★ When this WOULD be the correct answer
In a different scenario where a question states that clients cannot access any external resources, including IP addresses, and the default gateway is incorrectly configured, this option would be correct. For example, if the question specifies that the clients are unable to communicate outside their local subnet, then an incorrect default gateway would be the cause.
Why candidates choose this
Candidates might choose this option because they associate connectivity issues with routing problems, and the default gateway is a common troubleshooting point for network access issues, leading to confusion about the specific nature of the problem.
✗NAT overload is failing on the edge router.Wrong answer — click to see why▾
Why this is wrong here
NAT overload failing on the edge router would typically affect the ability to connect to the internet entirely, not just when using hostnames. Since clients can browse by IP, this indicates NAT is functioning correctly.
★ When this WOULD be the correct answer
In a scenario where clients cannot access any external resources, including both IP addresses and hostnames, and the question specifies issues with NAT configurations, this option could be correct if the NAT overload configuration is misconfigured or overloaded.
Why candidates choose this
Candidates might be drawn to this option due to a misunderstanding of NAT functionality, assuming that any internet connectivity issue must relate to NAT configurations, especially if they have seen similar questions in practice exams.
✗The switchport must be converted to a routed port.Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because the issue described pertains to DNS resolution, not layer 2 switching or routing. The problem is related to hostname resolution failures, which are not affected by the switchport type.
★ When this WOULD be the correct answer
In a different scenario, if the question stated that clients are unable to communicate with devices on different subnets and the switchport configuration was incorrectly set to access mode instead of routed mode, this option would be correct. It would indicate that the switchport needs to be configured to allow routing between VLANs.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of the network layers, thinking that routing issues at the switchport level could impact hostname resolution, especially if they are familiar with switch configurations.
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
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Related to this question
Learn chapter
Diagnosing DNS Record Issues — A, AAAA, CNAME, MX, NS, and PTR Records
Key term
Fully Qualified Domain Name
A Fully Qualified Domain Name is the complete and unambiguous website or server name that includes the host, domain, and top-level domain, leaving no room for guesswork.
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.
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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.