The correct answer is that the DHCP server has a duplicate client-ID issue, likely caused by two clients using the same client identifier. This is evident from the `show ip dhcp binding` output, where both clients—192.168.1.10 and 192.168.1.11—show identical hexadecimal client-ID strings. According to RFC 2131, a client-ID must uniquely identify a DHCP client; when two devices present the same identifier, the server treats them as a single client, leading to duplicate address bindings and potential IP conflicts. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your ability to interpret DHCP binding output and recognize that identical client-IDs, not MAC addresses, are the root cause of duplicate assignments—a common trap where candidates mistakenly blame hardware address duplication. Remember the key tip: client-ID overrides MAC address in DHCP operations, so always compare the full hexadecimal string, not the hardware address column, when troubleshooting duplicate bindings.
300-410 DHCP (IPv4 and IPv6) Practice Question
This 300-410 practice question tests your understanding of dhcp (ipv4 and ipv6). 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 network engineer runs the following command on Router R1:
R1# show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address Client-ID/ Lease expiration Type
Hardware address/
User name
192.168.1.10 0063.6973.636f.2e30. Mar 01 2020 12:00 AM Automatic
3030.3030.2e30.3030
312e.3130.3030.2e30
3030.312d.4574.682d
302f.31
192.168.1.11 0063.6973.636f.2e30. Mar 01 2020 12:00 AM Automatic
3030.3030.2e30.3030
312e.3130.3030.2e30
3030.312d.4574.682d
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 has a duplicate client-id issue, likely caused by two clients using the same client identifier.
The output shows two DHCP bindings with identical client identifiers (the long hexadecimal string). This indicates that two clients are using the same client-ID, which violates RFC 2131 and causes the DHCP server to treat them as the same client, leading to duplicate address assignments or conflicts. Option B correctly identifies this duplicate client-id issue.
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 DHCP server is functioning correctly with two unique bindings.
Why it's wrong here
The client-IDs are identical, so they are not unique.
✓
The DHCP server has a duplicate client-id issue, likely caused by two clients using the same client identifier.
Why this is correct
The hex client-id is identical for both bindings, indicating a duplicate.
Related concept
Read the scenario before looking for a memorised answer.
✗
The DHCP server has run out of addresses in the pool.
Why it's wrong here
There is no indication of pool exhaustion; only two bindings are shown.
✗
The DHCP server is not assigning addresses because the lease time is set to 0.
Why it's wrong here
Lease expiration is shown, but it does not indicate a lease time of 0.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between a duplicate client-ID and a normal DHCP binding, where candidates mistakenly assume two different IP addresses mean two unique clients, ignoring the identical client-ID field in the output.
Trap categories for this question
Command / output trap
There is no indication of pool exhaustion; only two bindings are shown.
Detailed technical explanation
How to think about this question
The client-ID in DHCP is used to uniquely identify a client, typically derived from the client's MAC address (e.g., '01' + MAC for Ethernet). When two clients present the same client-ID, the DHCP server cannot distinguish between them, often resulting in the same IP address being offered to both, causing IP conflicts. This scenario commonly occurs when virtual machines or containers are cloned without updating their client-ID, or when a client-ID is manually misconfigured.
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 practitioner preparing for the 300-410 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
DHCP (IPv4 and IPv6) — This question tests DHCP (IPv4 and IPv6) — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The DHCP server has a duplicate client-id issue, likely caused by two clients using the same client identifier. — The output shows two DHCP bindings with identical client identifiers (the long hexadecimal string). This indicates that two clients are using the same client-ID, which violates RFC 2131 and causes the DHCP server to treat them as the same client, leading to duplicate address assignments or conflicts. Option B correctly identifies this duplicate client-id issue.
What should I do if I get this 300-410 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.
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