- A
Check the DHCP server logs to see if it is receiving Discover messages.
Why wrong: If the router lacks a helper address, the server will not receive any Discover messages. Investigating server logs before confirming the relay configuration wastes time and skips a fundamental layer of the troubleshooting process.
- B
Verify that the ip helper-address command is configured on the router's VLAN 20 interface.
The router is the intervlan router, and the DHCP server is on a different subnet. For a DHCP Discover broadcast to cross VLANs, the router must have an IP helper-address pointing to the DHCP server's IP address on the VLAN 20 interface. Since all ports are up/up, the problem is almost certainly the missing relay. Checking this config directly addresses the most probable cause.
- C
Attempt to ping the DHCP server's IP address from the host's APIPA address.
Why wrong: The host's APIPA address (169.254.x.x) is a link-local address. Without a default gateway or a routable IP, pinging an address on a different subnet will not work, even if the DHCP server is reachable. This test does not confirm DHCP functionality and is not a standard troubleshooting step for DHCP failures.
- D
Restart the DHCP service on the server and recheck the host.
Why wrong: Restarting the DHCP service is a disruptive action and should not be the first step, especially when the root cause likely lies in the network configuration (missing relay). It does not address the underlying issue and may cause unnecessary downtime.
Quick Answer
The answer is to verify that the ip helper-address command is configured on the router’s VLAN 20 interface. When a host receives an APIPA address (169.254.x.x), it means the DHCP discovery broadcast failed to reach the server, which in this scenario resides on VLAN 1 while the client is on VLAN 20. Without a DHCP relay, broadcasts are confined to the local VLAN, so the router’s VLAN 20 interface must use the ip helper-address to forward those requests to the DHCP server. On the CCNA 200-301 v2 exam, this question tests your understanding of DHCP operation across VLANs and the common misstep of assuming a physical connectivity issue when all interfaces show up/up. A frequent trap is to check the switch port or DHCP server status first, but the APIPA address points directly to a missing relay. Memory tip: “APIPA means the helper is missing—check the interface facing the client.”
CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that their computer cannot access the network. The technician checks the computer's IP configuration and finds an APIPA address (169.254.x.x). The computer is connected to a switch port on VLAN 20. The DHCP server is located on VLAN 1. The technician then examines the router's interfaces using 'show ip interface brief' and sees that all interfaces shown are up/up. What should the technician do next?
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
Verify that the ip helper-address command is configured on the router's VLAN 20 interface.
The APIPA address (169.254.x.x) indicates the host failed to obtain a DHCP lease. Since the DHCP server is on VLAN 1 and the host is on VLAN 20, a DHCP relay (ip helper-address) must be configured on the router's VLAN 20 interface to forward DHCP broadcast messages to the server. The 'show ip interface brief' shows all interfaces are up/up, so the next logical step is to verify the relay configuration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Check the DHCP server logs to see if it is receiving Discover messages.
Why it's wrong here
If the router lacks a helper address, the server will not receive any Discover messages. Investigating server logs before confirming the relay configuration wastes time and skips a fundamental layer of the troubleshooting process.
- ✓
Verify that the ip helper-address command is configured on the router's VLAN 20 interface.
Why this is correct
The router is the intervlan router, and the DHCP server is on a different subnet. For a DHCP Discover broadcast to cross VLANs, the router must have an IP helper-address pointing to the DHCP server's IP address on the VLAN 20 interface. Since all ports are up/up, the problem is almost certainly the missing relay. Checking this config directly addresses the most probable cause.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Attempt to ping the DHCP server's IP address from the host's APIPA address.
Why it's wrong here
The host's APIPA address (169.254.x.x) is a link-local address. Without a default gateway or a routable IP, pinging an address on a different subnet will not work, even if the DHCP server is reachable. This test does not confirm DHCP functionality and is not a standard troubleshooting step for DHCP failures.
- ✗
Restart the DHCP service on the server and recheck the host.
Why it's wrong here
Restarting the DHCP service is a disruptive action and should not be the first step, especially when the root cause likely lies in the network configuration (missing relay). It does not address the underlying issue and may cause unnecessary downtime.
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.
✓Verify that the ip helper-address command is configured on the router's VLAN 20 interface.Correct answer▾
Why this is correct
The router is the intervlan router, and the DHCP server is on a different subnet. For a DHCP Discover broadcast to cross VLANs, the router must have an IP helper-address pointing to the DHCP server's IP address on the VLAN 20 interface. Since all ports are up/up, the problem is almost certainly the missing relay. Checking this config directly addresses the most probable cause.
✗Check the DHCP server logs to see if it is receiving Discover messages.Wrong answer — click to see why▾
Why this is wrong here
This action assumes the DHCP request has already reached the server; it bypasses verifying the network path that would deliver the broadcast to the server, which is the most likely missing piece.
✗Attempt to ping the DHCP server's IP address from the host's APIPA address.Wrong answer — click to see why▾
Why this is wrong here
Candidates might think that if the ping fails, the problem is network connectivity, but APIPA addresses are non-routable and the test itself is invalid in this context.
✗Restart the DHCP service on the server and recheck the host.Wrong answer — click to see why▾
Why this is wrong here
Many techs jump to rebooting a service when a simple configuration check would reveal the real problem. This violates the principle of least intrusive troubleshooting.
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the concept that a DHCP relay (ip helper-address) is required when the DHCP server is on a different subnet, and candidates mistakenly focus on server-side issues or ping tests instead of the router configuration.
Detailed technical explanation
How to think about this question
The ip helper-address command uses DHCP relay agent functionality defined in RFC 1542 to convert a DHCP broadcast into a unicast directed to the server's IP address. Without this command on the VLAN 20 interface, the router will not forward DHCP Discover/Request messages across VLANs, even if all interfaces are up/up. In real-world scenarios, misconfigured or missing ip helper-address is a common cause of APIPA addresses on multi-VLAN networks.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 200-301 question test?
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Verify that the ip helper-address command is configured on the router's VLAN 20 interface. — The APIPA address (169.254.x.x) indicates the host failed to obtain a DHCP lease. Since the DHCP server is on VLAN 1 and the host is on VLAN 20, a DHCP relay (ip helper-address) must be configured on the router's VLAN 20 interface to forward DHCP broadcast messages to the server. The 'show ip interface brief' shows all interfaces are up/up, so the next logical step is to verify the relay configuration.
What should I do if I get this 200-301 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
4 more ways this is tested on 200-301
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network administrator is troubleshooting a Windows 10 workstation that cannot access the internet. The workstation receives an IPv4 address starting with 169.254.x.x. The network uses DHCP, and other workstations on the same subnet are working correctly. What is the most likely cause of this issue?
medium- A.The workstation's DNS server settings are incorrect.
- ✓ B.The workstation's network cable is unplugged or faulty, preventing DHCP communication.
- C.The DHCP server has exhausted its address pool.
- D.The workstation's default gateway is misconfigured.
Why B: The 169.254.x.x address is an Automatic Private IP Addressing (APIPA) address assigned by Windows when DHCP fails. Since other workstations on the same subnet work correctly, the DHCP server and network are functional, isolating the issue to the specific workstation. A faulty or unplugged network cable would prevent the workstation from sending DHCP Discover messages, causing it to fall back to APIPA.
Variation 2. You are troubleshooting a PC connected to switch SW1. The PC cannot access the internet. SW1 is connected to router R1 via port G0/1. R1 provides default gateway and DHCP services. Analyze the provided show output and fix the connectivity issue so that the PC can ping 8.8.8.8. === Show output from R1 === <pre> R1# show ip interface brief Interface IP-Address OK? Method Status Protocol GigabitEthernet0/0 unassigned YES manual administratively down down GigabitEthernet0/1 10.0.0.1 YES NVRAM up up </pre> === Show output from PC === <pre> C:\> ipconfig Ethernet adapter Ethernet0: Connection-specific DNS Suffix . : IPv4 Address. . . . . . . . . . : 169.254.123.45 Subnet Mask . . . . . . . . . . : 255.255.0.0 Default Gateway . . . . . . . . : </pre> === Show output from SW1 === <pre> SW1# show vlan brief VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Gi0/1, Gi0/2, Gi0/3 </pre>
hard- ✓ A.Configure R1's interface G0/0 with IP address 192.168.1.1/24 and ensure the interface is not administratively down.
- B.Change the VLAN on SW1's port G0/2 to VLAN 10 and configure R1's subinterface G0/0.10 with IP 192.168.1.1/24.
- C.Enable DHCP snooping on SW1 and configure the port G0/2 as a trusted port.
- D.Configure a static IP address of 192.168.1.10/24 on the PC with default gateway 192.168.1.1.
Why A: The PC's APIPA address (169.254.x.x) indicates DHCP failure. The router's DHCP pool is correctly configured and has a lease, but the show output reveals that R1's interface G0/0 is administratively down and has no IP address. Without a working IP on G0/0, the router cannot serve DHCP or route traffic for VLAN 1, even though both the PC and the router are in the same VLAN. Option A fixes the root cause by assigning the correct subnet IP and bringing the interface up. Option B is incorrect because moving the PC to a different VLAN or creating subinterfaces does nothing to enable the router's physical interface where DHCP and routing must run. Option C is wrong because DHCP snooping or trust configurations are irrelevant when the router's own interface is down/unaddressed. Option D is a workaround that only masks the problem; the scenario requires a working DHCP service, and a static IP would not restore the intended design.
Variation 3. A network engineer is troubleshooting a workstation that cannot access the internet. The workstation is connected to a switch port configured for access VLAN 10. The switch is a Cisco 2960-X running IOS-XE. The engineer runs 'ipconfig /all' on the workstation and sees an IPv4 address of 169.254.123.45 with a subnet mask of 255.255.0.0. The engineer then connects to the switch and issues 'show interfaces vlan 10'. What is the most likely cause of the issue?
hard- A.The workstation is not configured to use DHCP.
- ✓ B.The switch's VLAN 10 SVI is administratively down.
- C.The switch port connecting the workstation is in a different VLAN.
- D.The DHCP server is not configured on the network.
Why B: The workstation has an APIPA address (169.254.x.x), which indicates it failed to obtain a DHCP lease. Since the switch's VLAN 10 SVI is administratively down, the workstation cannot reach the DHCP server (which may be on a different subnet or the SVI itself), causing the DHCP request to time out and the workstation to self-assign an APIPA address. Option B is correct because an administratively down SVI breaks Layer 3 connectivity for that VLAN, preventing DHCP traffic from being routed.
Variation 4. A user reports they cannot access any network resources. A network administrator runs ipconfig on the user's Windows PC and sees an IPv4 address of 169.254.45.3/16. The administrator then pings the default gateway 10.0.0.1, which fails, and uses traceroute to 10.0.0.1, which shows only '1 * * * Request timed out.' What is the most likely cause of the problem?
hard- A.The PC's DNS server address is incorrect.
- B.The switch port is in an administratively down state.
- C.The Ethernet cable is unplugged from the PC.
- ✓ D.The DHCP server is unreachable.
Why D: The 169.254.45.3/16 address is an Automatic Private IP Addressing (APIPA) address, assigned by Windows when a DHCP discovery fails. The failed ping and traceroute to the default gateway confirm that the PC has no IP connectivity to the network. Since the PC is on the same subnet as the DHCP server (10.0.0.0/24), the most likely cause is that the DHCP server is unreachable, preventing the PC from obtaining a valid IP address.
Last reviewed: Jun 25, 2026
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