Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
WLAN: Guest Mapped VLAN: 300 Switch interface Gi1/0/24 toward AP: switchport mode trunk switchport trunk allowed vlan 10,20,30
Clients can join the Guest SSID and authenticate successfully, but they never receive an IP address. The DHCP scope for the guest network exists on the server. Based on the exhibit, what is the most likely cause?
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 AP trunk is not allowing VLAN 300.
That prevents guest client traffic from reaching the proper VLAN.
B
Distractor review
The DHCP server must use TCP instead of UDP.
DHCP uses UDP.
C
Distractor review
The SSID name must match the DHCP pool name.
DHCP scopes do not depend on SSID naming.
D
Distractor review
The AP should be configured as an access port for VLAN 1.
Multiple SSIDs mapped to VLANs commonly require a trunk.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is to incorrectly assume that DHCP issues stem from the DHCP server configuration or protocol errors, such as believing DHCP must use TCP instead of UDP. Another tempting mistake is thinking the SSID name must match the DHCP pool name, which is false because DHCP scopes are based on VLAN subnets, not SSID naming. Additionally, some candidates mistakenly configure the access point port as an access port on VLAN 1, which prevents multiple VLANs from passing and breaks guest VLAN connectivity. These traps distract from the core issue of VLAN trunk misconfiguration preventing DHCP traffic.
Technical deep dive
How to think about this question
VLAN trunks are essential in wireless network deployments where multiple SSIDs are mapped to different VLANs. Each SSID corresponds to a VLAN that segregates traffic for security and management purposes. When a client connects to a guest SSID mapped to VLAN 300, the access point tags the client’s traffic with VLAN 300. This tagged traffic must traverse the trunk link between the access point and the switch, which must allow VLAN 300 to pass through. If VLAN 300 is not allowed on the trunk, the switch will drop the traffic, preventing it from reaching the DHCP server and other network resources. The decision process for troubleshooting DHCP issues in a wireless environment involves verifying VLAN trunk configurations. Since DHCP requests are broadcast packets tagged with the client’s VLAN, the trunk must carry the VLAN associated with the SSID. The DHCP server’s scope must match the VLAN subnet to assign IP addresses correctly. If the trunk does not allow the VLAN, DHCP requests never reach the server, resulting in clients authenticating successfully but failing to obtain IP addresses. This is a common misconfiguration in wireless VLAN deployments. A frequent exam trap is assuming that DHCP failure is due to server misconfiguration or protocol issues, such as using TCP instead of UDP, or that SSID names must match DHCP pool names. Another pitfall is configuring the access point port as an access port on VLAN 1, which restricts traffic to a single VLAN and breaks multi-SSID deployments. In practice, ensuring the trunk allows all necessary VLANs, including the guest VLAN, is critical for seamless wireless client connectivity and DHCP functionality.
KKey Concepts to Remember
- A VLAN trunk link between a switch and an access point must allow all VLANs that carry wireless client traffic to ensure proper network segmentation and connectivity.
- DHCP requests from wireless clients are tagged with the VLAN ID assigned to the SSID and must traverse the trunk link to reach the DHCP server on the correct VLAN.
- If a VLAN is not allowed on a trunk port, traffic tagged with that VLAN is dropped, preventing clients from obtaining IP addresses via DHCP.
- Multiple SSIDs on a wireless LAN controller or access point are typically mapped to different VLANs to separate traffic and apply distinct policies.
- DHCP uses UDP as its transport protocol, and changing it to TCP is not valid or supported in standard network configurations.
- The SSID name is independent of DHCP scope names; DHCP scopes are defined by IP subnet and VLAN, not by SSID naming conventions.
- Configuring an access point port as an access port on VLAN 1 restricts it to a single VLAN and prevents multiple SSIDs mapped to different VLANs from functioning properly.
- Wireless client authentication can succeed without DHCP if the VLAN tagging and trunk configuration are incorrect, but clients will lack 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?
A VLAN trunk link between a switch and an access point must allow all VLANs that carry wireless client traffic to ensure proper network segmentation and connectivity.
What is the correct answer to this question?
The correct answer is: The AP trunk is not allowing VLAN 300. — The Guest SSID is mapped to VLAN 300, but the switch trunk toward the AP allows only VLANs 10,20,30. Client traffic for the guest WLAN never reaches the correct VLAN upstream, so DHCP requests for that WLAN fail. Authentication can still succeed depending on how the WLAN is designed.
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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