Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
VLAN 70 DHCP scope: network 10.70.70.0 255.255.255.0 default-router 10.70.70.1 Client tests: - ping 192.0.2.50 = success - open http://192.0.2.50 = success - open http://portal.branch.lab = fail
Based on the exhibit, why are clients in VLAN 70 failing to resolve hostnames even though they can reach remote IP addresses?
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
The clients are missing valid DNS server information.
This is correct because hostname-based access fails while direct IP access works, and the scope shown does not provide a DNS server option.
B
Distractor review
The default gateway must be removed from the DHCP scope.
This is wrong because the default gateway is needed for routed communication and is not the cause of hostname-only failure.
C
Distractor review
The clients must use PPP before DNS works.
This is wrong because PPP is unrelated to ordinary client DNS resolution in this LAN scenario.
D
Distractor review
The VLAN must be converted to the native VLAN on all trunks.
This is wrong because the symptoms isolate the problem to name resolution rather than general forwarding.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is to mistake the inability to resolve hostnames as a routing or VLAN trunking problem. Candidates might incorrectly believe that removing the default gateway or converting the VLAN to the native VLAN on trunks will resolve the issue. However, these options do not address DNS resolution, which is an application-layer service independent of Layer 3 forwarding. The trap arises because clients can reach remote IP addresses, misleading candidates to focus on routing or VLAN configuration rather than missing DNS server information in the DHCP scope.
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 clients to access resources by name rather than numeric IPs. In a VLAN environment, clients rely on DHCP to provide not only IP addressing and default gateway information but also DNS server addresses. Without a valid DNS server configured, clients cannot resolve hostnames, even though IP connectivity remains functional. This separation of IP routing and name resolution is fundamental in Cisco networking and the CCNA exam context. When troubleshooting VLAN client connectivity issues, it is essential to verify the DHCP scope configuration. The DHCP scope must include the DNS server option to enable clients to resolve hostnames. If the DHCP scope only provides an IP address and default gateway but omits the DNS server, clients will fail to resolve domain names despite successful Layer 3 routing to remote IP addresses. This behavior highlights the difference between routing functionality and application-layer services like DNS. A common exam trap is to confuse routing or VLAN trunking issues with DNS resolution problems. Candidates might incorrectly assume that removing the default gateway or changing VLAN trunk configurations will fix hostname resolution failures. However, these changes do not affect DNS functionality. The practical networking implication is that ensuring DHCP scopes include DNS server information is vital for full IP service usability, especially in segmented VLAN environments where clients depend on DHCP for configuration.
KKey Concepts to Remember
- DNS translates human-readable hostnames into IP addresses, enabling clients to access network resources by name rather than numeric IPs.
- DHCP scopes must include DNS server information to allow clients in VLANs to resolve hostnames successfully.
- Clients can have full Layer 3 connectivity and still fail hostname resolution if DNS server addresses are missing from DHCP configuration.
- The default gateway option in DHCP is necessary for routing but does not influence DNS resolution or hostname access.
- VLAN trunk configurations and native VLAN settings affect Layer 2 forwarding but do not impact DNS-based hostname resolution.
- Troubleshooting IP services requires distinguishing between routing issues and application-layer service failures like DNS.
- Cisco devices rely on DHCP options to provide critical IP services, including DNS, to clients within VLANs.
- Hostname resolution failures with successful IP connectivity typically indicate missing or incorrect DNS server information in DHCP.
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.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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 clients to access network resources by name rather than numeric IPs.
What is the correct answer to this question?
The correct answer is: The clients are missing valid DNS server information. — The strongest explanation is that the clients are missing valid DNS server information. In practical terms, successful reachability to remote IP addresses proves that Layer 3 forwarding is working. The failure occurs only when a hostname is used, which points to a naming service problem rather than a general connectivity problem. The DHCP scope shown provides an address and default gateway, but no DNS server option is defined. This is a very realistic IP-services troubleshooting pattern because the network path works while application usability still fails.
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.
Discussion
Loading comments…
Sign in to join the discussion.