hardMultiple ChoiceObjective-mapped
300-410 Practice Question: The default DHCPv6 client DUID type on a Cisco…
What is the default DHCPv6 client DUID type on a Cisco IOS-XE router?
⚠ Common exam trap
Cisco often tests the default DUID type by contrasting it with DUID-LLT, leading candidates to mistakenly choose DUID-LLT because they recall that DHCPv6 clients can use a time-based identifier, but they forget that Cisco defaults to the simpler, non-timestamped DUID-LL.
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
✓
DUID-LL (Link-Layer)
Cisco IOS-XE routers default to DUID-LL (Link-Layer) as the DHCPv6 client DUID type, as defined in RFC 8415. This DUID is generated using the router's link-layer address (MAC address) without a timestamp, making it stable across reboots. The DUID-LL is the default because it provides a consistent identifier without requiring clock synchronization or enterprise registration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DUID-LLT (Link-Layer plus Time)
Why it's wrong here
DUID-LLT is used by some implementations but not the default on Cisco IOS-XE.
- ✗
DUID-EN (Enterprise Number)
Why it's wrong here
DUID-EN is used for vendor-specific DUIDs, not the default.
- ✓
DUID-LL (Link-Layer)
Why this is correct
Cisco IOS-XE defaults to DUID-LL for DHCPv6 clients.
- ✗
DUID-UUID (Universally Unique Identifier)
Why it's wrong here
DUID-UUID is not a standard DUID type in RFC 8415.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.