- A
Clients on the 192.168.1.0/24 subnet will receive IP addresses from the local DHCP pool, and the ip helper-address will forward DHCP requests to 192.168.2.2, causing duplicate offers.
The local DHCP server will respond to requests, but the helper address will also forward broadcasts to the remote server, leading to duplicate DHCP offers and potential address conflicts.
- B
The ip helper-address command will be ignored because the router is the DHCP server for that subnet.
Why wrong: The ip helper-address is not ignored; it still forwards broadcasts to the specified server, as the router does not automatically disable it when acting as a DHCP server.
- C
The excluded-address range is misconfigured because it includes the router's own interface IP, which will prevent the router from functioning.
Why wrong: Excluding the router's own IP is a best practice to avoid conflicts; the router will still function normally.
- D
The DHCP pool will not assign addresses because the network statement does not match the interface subnet exactly.
Why wrong: The network 192.168.1.0 255.255.255.0 matches the interface subnet exactly, so it is valid.
Quick Answer
The correct answer is that clients on the 192.168.1.0/24 subnet will receive duplicate IP offers because the router is acting as both a local DHCP server via pool POOL1 and a DHCP relay agent via the ip helper-address 192.168.2.2. When a client sends a broadcast DHCPDISCOVER, the router’s local server processes it and generates an offer from the pool, while simultaneously the ip helper-address converts that broadcast into a unicast and forwards it to the remote server at 192.168.2.2, which also replies with an offer. This configuration is a classic trap on the Cisco CCNP ENARSI 300-410 exam, testing your understanding that ip helper-address does not disable the local DHCP server—both functions operate independently on the same interface. A common mistake is assuming the helper-address overrides the local pool, but in reality, the router will relay the request even if it can serve it locally. Memory tip: “Local server and relay coexist—duplicate offers are the twist.”
300-410 DHCP (IPv4 and IPv6) Practice Question
This 300-410 practice question tests your understanding of dhcp (ipv4 and ipv6). This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Examine the following DHCP configuration on router R1:
ip dhcp excluded-address 192.168.1.1 192.168.1.10
!
ip dhcp pool POOL1 network 192.168.1.0 255.255.255.0
default-router 192.168.1.1 dns-server 8.8.8.8 lease 0 2 30 !
interface GigabitEthernet0/0 ip address 192.168.1.1 255.255.255.0 ip helper-address 192.168.2.2 no shutdown
What is the effect of this configuration?
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
Clients on the 192.168.1.0/24 subnet will receive IP addresses from the local DHCP pool, and the ip helper-address will forward DHCP requests to 192.168.2.2, causing duplicate offers.
Option A is correct because the router R1 is configured as a DHCP server for the 192.168.1.0/24 subnet via the local pool POOL1, and the ip helper-address 192.168.2.2 on the same interface will forward broadcast DHCP requests from clients to the remote DHCP server at 192.168.2.2. This results in both the local pool and the remote server offering IP addresses, leading to duplicate offers on the subnet.
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.
- ✓
Clients on the 192.168.1.0/24 subnet will receive IP addresses from the local DHCP pool, and the ip helper-address will forward DHCP requests to 192.168.2.2, causing duplicate offers.
Why this is correct
The local DHCP server will respond to requests, but the helper address will also forward broadcasts to the remote server, leading to duplicate DHCP offers and potential address conflicts.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The ip helper-address command will be ignored because the router is the DHCP server for that subnet.
Why it's wrong here
The ip helper-address is not ignored; it still forwards broadcasts to the specified server, as the router does not automatically disable it when acting as a DHCP server.
- ✗
The excluded-address range is misconfigured because it includes the router's own interface IP, which will prevent the router from functioning.
Why it's wrong here
Excluding the router's own IP is a best practice to avoid conflicts; the router will still function normally.
- ✗
The DHCP pool will not assign addresses because the network statement does not match the interface subnet exactly.
Why it's wrong here
The network 192.168.1.0 255.255.255.0 matches the interface subnet exactly, so it is valid.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a router acting as a DHCP server on an interface will automatically suppress the ip helper-address relay function, but in reality, both processes operate independently, leading to duplicate offers.
Detailed technical explanation
How to think about this question
The ip helper-address command uses UDP port 67 (DHCP server) and 68 (DHCP client) to relay broadcasts as unicasts to the specified server, per RFC 1542. When a router is both a DHCP server and a relay agent on the same interface, it will respond locally and also forward the request, leading to multiple offers that can cause client confusion or lease conflicts. In real-world scenarios, this misconfiguration often results in clients receiving IP addresses from unexpected scopes, especially in branch offices with local and central DHCP servers.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
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FAQ
Questions learners often ask
What does this 300-410 question test?
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: Clients on the 192.168.1.0/24 subnet will receive IP addresses from the local DHCP pool, and the ip helper-address will forward DHCP requests to 192.168.2.2, causing duplicate offers. — Option A is correct because the router R1 is configured as a DHCP server for the 192.168.1.0/24 subnet via the local pool POOL1, and the ip helper-address 192.168.2.2 on the same interface will forward broadcast DHCP requests from clients to the remote DHCP server at 192.168.2.2. This results in both the local pool and the remote server offering IP addresses, leading to duplicate offers on the subnet.
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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Last reviewed: Jun 24, 2026
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.
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