The correct answer is that the DHCP pool includes the network and broadcast addresses, which must be excluded using the 'ip dhcp excluded-address' command. On a Cisco switch acting as a DHCP server for the 192.168.1.0/24 subnet, the addresses 192.168.1.0 (network ID) and 192.168.1.255 (broadcast) are reserved and cannot be leased to hosts. When a client requests an IP, the server may attempt to assign one of these reserved addresses, causing a conflict that prevents the DHCP lease from completing successfully. This scenario tests your understanding of DHCP pool configuration on the CCNA 200-301 v2 exam, where a common trap is forgetting that the default pool includes all addresses in the subnet unless explicitly excluded. A key memory tip is to think of the network and broadcast addresses as the "bookends" of the subnet—they hold the range together but cannot be given out, so always exclude them first with the 'ip dhcp excluded-address' command.
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. 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.
Exhibit
Switch# show ip dhcp pool VLAN10
Pool VLAN10 :
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 192.168.1.0 / 24
Total addresses : 254
Leased addresses : 0
Pending event : none
Automatic bindings :
Lease time : 1 day
Next network numbers :
192.168.1.0
Switch# show ip dhcp server statistics
Memory usage : 26740
Address pools : 1
Database agents : 0
Automatic bindings : 0
Manual bindings : 0
Expired bindings : 0
Malformed messages : 0
Message Received:
BOOTREQUEST : 0
DHCPDISCOVER : 0
DHCPREQUEST : 0
DHCPDECLINE : 0
DHCPRELEASE : 0
DHCPINFORM : 0
Switch# show ip dhcp conflict
IP address Detection method Detection time
192.168.1.1 Ping Jan 1 00:00:00.000
192.168.1.254 Ping Jan 1 00:00:00.000
A network administrator has configured a Cisco switch as a DHCP server for the 192.168.1.0/24 subnet. Hosts in VLAN 10 are unable to obtain IP addresses via DHCP. The switch's SVI for VLAN 10 is up/up. What is the most likely cause of the problem?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Switch# show ip dhcp pool VLAN10
Pool VLAN10 :
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 192.168.1.0 / 24
Total addresses : 254
Leased addresses : 0
Pending event : none
Automatic bindings :
Lease time : 1 day
Next network numbers :
192.168.1.0
Switch# show ip dhcp server statistics
Memory usage : 26740
Address pools : 1
Database agents : 0
Automatic bindings : 0
Manual bindings : 0
Expired bindings : 0
Malformed messages : 0
Message Received:
BOOTREQUEST : 0
DHCPDISCOVER : 0
DHCPREQUEST : 0
DHCPDECLINE : 0
DHCPRELEASE : 0
DHCPINFORM : 0
Switch# show ip dhcp conflict
IP address Detection method Detection time
192.168.1.1 Ping Jan 1 00:00:00.000
192.168.1.254 Ping Jan 1 00:00:00.000
A
The VLAN 10 SVI is not configured with an IP address in the 192.168.1.0/24 subnet.
Why wrong: The SVI is up/up, but its IP address is not shown; however, DHCP server operation does not require the SVI to be in the same subnet as the pool.
B
The DHCP server is including the network and broadcast addresses in the pool, causing conflicts. Use the 'ip dhcp excluded-address' command to exclude them.
The conflict detection shows that addresses 192.168.1.1 (network) and 192.168.1.254 (broadcast) are in conflict. These should be excluded to prevent the DHCP server from leasing them.
C
DHCP snooping is blocking DHCP messages on the switch port connected to the hosts.
Why wrong: DHCP snooping is not shown in the exhibit; the statistics show 0 DHCP messages received, which suggests the server is not receiving them at all.
D
The DHCP pool is not bound to VLAN 10. Use the 'vlan' command under the pool configuration.
Why wrong: DHCP pools are not bound to VLANs in Cisco IOS; they are associated with subnets. The pool is correctly configured for the 192.168.1.0/24 subnet.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The DHCP server is including the network and broadcast addresses in the pool, causing conflicts. Use the 'ip dhcp excluded-address' command to exclude them.
Option B is correct. The most likely cause is that the DHCP server pool includes the network (192.168.1.0) and broadcast (192.168.1.255) addresses, which are reserved and cannot be leased. When a host requests an IP, the server may attempt to assign one of these addresses, causing a conflict and preventing successful DHCP lease completion. Using the 'ip dhcp excluded-address' command to exclude these addresses from the pool resolves the issue. Option A is not the best answer because the SVI for VLAN 10 is up/up and must already have an IP address in the 192.168.1.0/24 subnet for the DHCP server to offer addresses to that subnet; if it were missing, DHCP would fail completely, but the symptom would likely be no offers at all, not address conflicts. The problem described is consistent with the pool including reserved addresses, which is a common misconfiguration.
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.
✗
The VLAN 10 SVI is not configured with an IP address in the 192.168.1.0/24 subnet.
Why it's wrong here
The SVI is up/up, but its IP address is not shown; however, DHCP server operation does not require the SVI to be in the same subnet as the pool.
✓
The DHCP server is including the network and broadcast addresses in the pool, causing conflicts. Use the 'ip dhcp excluded-address' command to exclude them.
Why this is correct
The conflict detection shows that addresses 192.168.1.1 (network) and 192.168.1.254 (broadcast) are in conflict. These should be excluded to prevent the DHCP server from leasing them.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
DHCP snooping is blocking DHCP messages on the switch port connected to the hosts.
Why it's wrong here
DHCP snooping is not shown in the exhibit; the statistics show 0 DHCP messages received, which suggests the server is not receiving them at all.
✗
The DHCP pool is not bound to VLAN 10. Use the 'vlan' command under the pool configuration.
Why it's wrong here
DHCP pools are not bound to VLANs in Cisco IOS; they are associated with subnets. The pool is correctly configured for the 192.168.1.0/24 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.
✓The DHCP server is including the network and broadcast addresses in the pool, causing conflicts. Use the 'ip dhcp excluded-address' command to exclude them.Correct answer▾
Why this is correct
The conflict detection shows that addresses 192.168.1.1 (network) and 192.168.1.254 (broadcast) are in conflict. These should be excluded to prevent the DHCP server from leasing them.
✗The VLAN 10 SVI is not configured with an IP address in the 192.168.1.0/24 subnet.Wrong answer — click to see why▾
Why this is wrong here
The SVI must have an IP address for routing, but the DHCP server can serve addresses from any pool regardless of the SVI's subnet. The issue is with the pool itself.
✗DHCP snooping is blocking DHCP messages on the switch port connected to the hosts.Wrong answer — click to see why▾
Why this is wrong here
If DHCP snooping were blocking messages, the 'Malformed messages' counter might increase, but the server would still receive some messages. The zero count indicates no messages are reaching the server.
✗The DHCP pool is not bound to VLAN 10. Use the 'vlan' command under the pool configuration.Wrong answer — click to see why▾
Why this is wrong here
There is no 'vlan' command under a DHCP pool. The pool serves all hosts in the subnet regardless of VLAN association.
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
Learners often overlook that the DHCP pool's range must exclude network and broadcast addresses; they may incorrectly suspect DHCP snooping, an SVI misconfiguration, or a missing VLAN binding instead.
Trap categories for this question
Command / output trap
The SVI is up/up, but its IP address is not shown; however, DHCP server operation does not require the SVI to be in the same subnet as the pool.
Detailed technical explanation
How to think about this question
When a Cisco switch acts as a DHCP server, the 'ip dhcp pool' defines a range of addresses from the specified network; by default, all addresses in the subnet are available for lease unless excluded. The network and broadcast addresses (first and last in the subnet) are reserved by RFC 950 and cannot be assigned to hosts; attempting to lease them causes the DHCP server to send an offer that the client may reject or that leads to IP conflicts. In real-world scenarios, administrators often forget to exclude these addresses, especially when using a /24 subnet, leading to intermittent DHCP failures that are hard to diagnose.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Network Services and Security — This question tests Network Services and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The DHCP server is including the network and broadcast addresses in the pool, causing conflicts. Use the 'ip dhcp excluded-address' command to exclude them. — Option B is correct. The most likely cause is that the DHCP server pool includes the network (192.168.1.0) and broadcast (192.168.1.255) addresses, which are reserved and cannot be leased. When a host requests an IP, the server may attempt to assign one of these addresses, causing a conflict and preventing successful DHCP lease completion. Using the 'ip dhcp excluded-address' command to exclude these addresses from the pool resolves the issue. Option A is not the best answer because the SVI for VLAN 10 is up/up and must already have an IP address in the 192.168.1.0/24 subnet for the DHCP server to offer addresses to that subnet; if it were missing, DHCP would fail completely, but the symptom would likely be no offers at all, not address conflicts. The problem described is consistent with the pool including reserved addresses, which is a common misconfiguration.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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