CCNA Network Infrastructure and Connectivity Practice Question
Which IPv6 protocol function replaces ARP?
⚠ Common exam trap
Be careful not to confuse protocols that manage IP addresses or routing with those that resolve addresses.
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
✓
Neighbor Discovery
IPv6 uses Neighbor Discovery Protocol to resolve Layer 3-to-Layer 2 information and perform related local-link functions such as router discovery and address resolution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DHCPv6
Why it's wrong here
DHCPv6 is responsible for assigning stateful IPv6 addresses and delivering configuration options such as DNS server addresses and domain names, but it never resolves an IPv6 address to a MAC address on the local segment. The ARP replacement function requires direct link-local communication; DHCPv6's client-server exchange is not used for neighbor cache lookups. Without Neighbor Discovery, DHCPv6 cannot tell you the MAC address that owns a given IPv6 address.
When this WOULD be correct
If the exam question asked about protocols involved in IPv6 address assignment or configuration, such as 'Which protocol is responsible for dynamically assigning IPv6 addresses to devices?', then DHCPv6 would be the correct answer.
- ✓
Neighbor Discovery
Why this is correct
Neighbor Discovery (ND) replaces ARP by using ICMPv6 Neighbor Solicitation and Neighbor Advertisement messages to dynamically resolve IPv6 addresses to link-layer MAC addresses. It also handles router discovery, prefix discovery, and duplicate address detection, making it the core protocol for link-local interactions in IPv6. ND tracks neighbor reachability state in the neighbor cache, just as ARP did in IPv4.
- ✗
EUI-64
Why it's wrong here
EUI-64 is a deterministic algorithm that creates a 64-bit interface identifier by inserting FFFE into the middle of a 48-bit MAC address, optionally with the universal/local bit flipped. This only generates a host's own interface ID for autoconfiguration; it performs no network signaling and cannot discover or verify a neighbor's link-layer address. Thus it is an addressing method, not a resolution protocol.
When this WOULD be correct
If the exam question asked about methods for generating IPv6 addresses or identifiers, specifically in the context of creating unique addresses from MAC addresses, then EUI-64 would be the correct answer.
- ✗
SLAAC
Why it's wrong here
SLAAC lets a host automatically configure its own global IPv6 address by combining a prefix from Router Advertisements with its own interface identifier, without needing a stateful server. However, once an address is chosen, the host still relies on Neighbor Discovery to resolve the next-hop router's MAC address or to check for duplicates via Duplicate Address Detection. Because SLAAC never answers "which MAC owns this IPv6 address," it is not the ARP replacement.
When this WOULD be correct
If the exam question asked which protocol is responsible for automatically configuring IPv6 addresses without requiring a DHCP server, then SLAAC would be the correct answer. This would focus on address assignment rather than address resolution.
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.
✓Neighbor DiscoveryCorrect answer▾
Why this is correct
Neighbor Discovery (ND) replaces ARP by using ICMPv6 Neighbor Solicitation and Neighbor Advertisement messages to dynamically resolve IPv6 addresses to link-layer MAC addresses. It also handles router discovery, prefix discovery, and duplicate address detection, making it the core protocol for link-local interactions in IPv6. ND tracks neighbor reachability state in the neighbor cache, just as ARP did in IPv4.
✗DHCPv6Wrong answer — click to see why▾
Why this is wrong here
DHCPv6 is not a protocol that replaces ARP; instead, it is used for assigning IP addresses and configuration information to IPv6 devices. ARP is replaced by the Neighbor Discovery Protocol in IPv6, which performs similar functions for address resolution.
★ When this WOULD be the correct answer
If the exam question asked about protocols involved in IPv6 address assignment or configuration, such as 'Which protocol is responsible for dynamically assigning IPv6 addresses to devices?', then DHCPv6 would be the correct answer.
Why candidates choose this
Candidates may find DHCPv6 tempting because it is a well-known protocol associated with IP address management, leading them to mistakenly associate it with the address resolution functions that ARP performed in IPv4.
✗EUI-64Wrong answer — click to see why▾
Why this is wrong here
EUI-64 is not a protocol but a method for generating IPv6 interface identifiers. It does not perform the function of resolving link-layer addresses like ARP does in IPv4.
★ When this WOULD be the correct answer
If the exam question asked about methods for generating IPv6 addresses or identifiers, specifically in the context of creating unique addresses from MAC addresses, then EUI-64 would be the correct answer.
Why candidates choose this
Candidates may confuse EUI-64 with address resolution functions due to its association with IPv6 addressing, leading them to mistakenly believe it plays a role similar to ARP.
✗SLAACWrong answer — click to see why▾
Why this is wrong here
SLAAC (Stateless Address Autoconfiguration) is a method for automatically configuring IPv6 addresses but does not perform the function of resolving link-layer addresses like ARP does in IPv4. Therefore, it cannot replace ARP in IPv6.
★ When this WOULD be the correct answer
If the exam question asked which protocol is responsible for automatically configuring IPv6 addresses without requiring a DHCP server, then SLAAC would be the correct answer. This would focus on address assignment rather than address resolution.
Why candidates choose this
Candidates might choose SLAAC because it is associated with IPv6 address configuration, leading to confusion between address assignment and address resolution functions, making it seem relevant to the question.
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?”
Visual reference
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
Related to this question
Learn chapter
IPv4 Addressing and Address Classes
Key term
IPv6
IPv6 is the most recent version of the Internet Protocol, designed to replace IPv4 by providing a vastly larger number of unique addresses and improved network features.
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.