The correct statement is that the interface will allow DHCP server messages only from sources matching SERVER_ACL. This is because the DHCP guard policy configured with device-role server explicitly designates the interface as a trusted DHCP server, but the match server access-list SERVER_ACL clause restricts which server source addresses are permitted; any DHCP server message not matching the ACL is dropped. On the Cisco CCNP ENARSI 300-410 exam, this configuration tests your understanding of how DHCP guard policies enforce role-based filtering on IPv6 networks, often appearing in questions that mix device-role client and server with ACLs to create traps where candidates forget that server role still requires ACL validation. A common mistake is assuming device-role server allows all DHCP server traffic, but the ACL is mandatory for granular control. Remember the memory tip: “Server role opens the door, but the ACL holds the key.”
300-410 IPv6 First Hop Security Practice Question
This 300-410 practice question tests your understanding of ipv6 first hop security. 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 partial IPv6 DHCP guard configuration:
ipv6 dhcp guard policy DHCP_GUARD
device-role server
match server access-list SERVER_ACL
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The interface will allow DHCP server messages only from sources matching SERVER_ACL.
DHCP guard policy with device-role server allows DHCP server messages only if they match the access-list. The interface applies the policy to filter DHCP messages.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 interface will allow DHCP server messages only from sources matching SERVER_ACL.
Why this is correct
The 'match server' clause restricts which servers are trusted, and the policy is applied to the interface.
Related concept
Standard ACLs match source addresses.
✗
The interface will block all DHCP server messages.
Why it's wrong here
The policy allows server messages that match the ACL, not block all.
✗
The interface will allow all DHCP client messages.
Why it's wrong here
The policy focuses on server messages; client messages are not explicitly filtered.
✗
The interface will drop all DHCP messages.
Why it's wrong here
Only server messages not matching the ACL are dropped.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 300-410 ACL questions on filtering logic and placement.
IPv6 First Hop Security — This question tests IPv6 First Hop Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The interface will allow DHCP server messages only from sources matching SERVER_ACL. — DHCP guard policy with device-role server allows DHCP server messages only if they match the access-list. The interface applies the policy to filter DHCP messages.
What should I do if I get this 300-410 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 300-410 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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