CCNA Network Services and Security Practice Question
Which two statements accurately describe why DNS issues can look like general connectivity problems to users?
⚠ Common exam trap
A common exam trap is assuming that DNS failure means the default gateway or other network infrastructure is missing or malfunctioning. Candidates might incorrectly link DNS issues to routing failures or DHCP and NTP outages, which are separate services. This misunderstanding leads to wasted troubleshooting effort on routing tables or gateway configurations when the real problem lies in DNS server availability or client resolver settings. The exam tests your ability to isolate DNS as an application-layer service distinct from network-layer connectivity.
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
✓
Users often access services by name, so failed name resolution can feel like total connectivity loss.
DNS issues can look like general connectivity problems because many users think in terms of names, not IP addresses. In practical terms, they may report that 'the network is down' when the actual routed path works but hostname resolution does not. That is why testing by IP versus name is such a useful troubleshooting step. The distinction between transport reachability and naming is critical in user-facing support.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Users often access services by name, so failed name resolution can feel like total connectivity loss.
Why this is correct
DNS translates human-friendly domain names into IP addresses, so when name resolution fails, client applications cannot even initiate a session to a server. Because users rarely type raw IP addresses, every attempted connection appears to fail, making a single DNS outage feel identical to a complete network outage. The data path may be fully operational, but the user perceives total connectivity loss.
- ✓
Testing by IP address versus hostname can help distinguish DNS issues from raw path issues.
Why this is correct
A classic troubleshooting method is to compare connectivity when using a hostname versus its literal IP address. If the IP-based connection succeeds but the hostname-based attempt fails, the problem is almost certainly in DNS resolution rather than in the underlying network path. If both fail, the fault lies deeper in the L2/L3 path, such as routing, switching, or firewall filtering, not in name lookup.
- ✗
DNS failure automatically means the default gateway is missing.
Why it's wrong here
A missing default gateway would prevent traffic from leaving the local subnet, so all off-subnet IP communication would fail regardless of domain names. DNS failure, by contrast, is typically a name-resolution problem caused by an unreachable DNS server, a misconfigured resolver, or a firewall blocking UDP/TCP port 53. The local route and gateway can be perfectly healthy while DNS resolution is broken, because these are separate functions at different layers of the network.
When this WOULD be correct
In a question that specifically asks about scenarios where DNS failures directly impact the default gateway's functionality, such as in a misconfigured network where DNS settings are tied to gateway operations, this option could be correct. For instance, if a network's routing relies on DNS resolution for gateway identification, a DNS failure could indeed lead to a perceived loss of the default gateway.
- ✗
If DNS fails, DHCP and NTP must also fail immediately.
Why it's wrong here
DNS, DHCP, and NTP are independent protocols operating at different layers and on different ports: DNS uses UDP/TCP 53 for name resolution, DHCP uses UDP 67/68 for address assignment, and NTP uses UDP 123 for time synchronization. An outage of your DNS server does not directly stop the DHCP server from leasing addresses or the NTP server from providing time. They could be affected only if a common infrastructure failure, such as a switch or power outage, happens to impact them together.
When this WOULD be correct
If the exam question asked about the dependencies between network services and specified a scenario where DNS, DHCP, and NTP were configured on the same server, and that server experienced a complete failure, then this option could be correct. In that case, the failure of DNS could imply a broader service outage affecting DHCP and NTP.
- ✗
DNS replaces the need for routing between subnets.
Why it's wrong here
DNS only performs name-to-address translation; it does not make forwarding decisions or move packets between subnets. Routing is the layer 3 process that examines destination IP addresses and forwards packets across routers to different networks. If routing were absent, hosts could not reach remote subnets even with perfect DNS, and in many cases the DNS server itself might reside on a different subnet that requires routing to reach.
When this WOULD be correct
In a question focused on the role of DNS in network architecture, if it asked whether DNS can eliminate the need for routing protocols in specific scenarios, option E could be correct if discussing a hypothetical network design that relies solely on DNS for service discovery within a single subnet.
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.
✓Users often access services by name, so failed name resolution can feel like total connectivity loss.Correct answer▾
Why this is correct
DNS translates human-friendly domain names into IP addresses, so when name resolution fails, client applications cannot even initiate a session to a server. Because users rarely type raw IP addresses, every attempted connection appears to fail, making a single DNS outage feel identical to a complete network outage. The data path may be fully operational, but the user perceives total connectivity loss.
✗DNS failure automatically means the default gateway is missing.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because a DNS failure does not inherently indicate that the default gateway is missing; DNS and the default gateway are separate components of network connectivity. Users can experience DNS issues while still having a valid default gateway configured.
★ When this WOULD be the correct answer
In a question that specifically asks about scenarios where DNS failures directly impact the default gateway's functionality, such as in a misconfigured network where DNS settings are tied to gateway operations, this option could be correct. For instance, if a network's routing relies on DNS resolution for gateway identification, a DNS failure could indeed lead to a perceived loss of the default gateway.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of how network layers interact, leading them to believe that DNS issues must affect all aspects of connectivity, including the default gateway.
✗If DNS fails, DHCP and NTP must also fail immediately.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because DNS failure does not inherently cause DHCP and NTP services to fail; they operate independently. A DNS issue may affect name resolution, but DHCP and NTP can still function normally if their configurations are intact.
★ When this WOULD be the correct answer
If the exam question asked about the dependencies between network services and specified a scenario where DNS, DHCP, and NTP were configured on the same server, and that server experienced a complete failure, then this option could be correct. In that case, the failure of DNS could imply a broader service outage affecting DHCP and NTP.
Why candidates choose this
Candidates might choose this option due to a misunderstanding of how network services interact, mistakenly believing that all services dependent on DNS must fail together, reflecting a common misconception about service dependencies.
✗DNS replaces the need for routing between subnets.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because DNS does not replace the need for routing; routing is still essential for directing traffic between different subnets regardless of DNS functionality.
★ When this WOULD be the correct answer
In a question focused on the role of DNS in network architecture, if it asked whether DNS can eliminate the need for routing protocols in specific scenarios, option E could be correct if discussing a hypothetical network design that relies solely on DNS for service discovery within a single subnet.
Why candidates choose this
Candidates might choose this option due to a misunderstanding of DNS's role in network communication, mistakenly believing that DNS can handle routing tasks, leading to confusion about the functions of different network components.
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
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
Diagnosing DNS Record Issues — A, AAAA, CNAME, MX, NS, and PTR Records
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.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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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.