CCNA Network Infrastructure and Connectivity Practice Question
Which two statements accurately describe IPv6 link-local addresses?
⚠ Common exam trap
Remember that link-local addresses are not routable and are not a fallback for DHCPv6. They are essential for local communications.
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
✓
They are used for communication on the local segment only.
IPv6 link-local addresses are designed for communication on the local segment only. In plain language, they allow devices to talk to nearby neighbors without needing globally routable addresses. They play an important role in IPv6 functions such as Neighbor Discovery and are commonly used when hosts communicate with the default gateway on the same link. These addresses are normal and expected in IPv6 environments. They are not globally Internet-routable, and they are not just emergency fallbacks for DHCPv6 failure. The two correct answers are the ones that preserve their local-link purpose and their importance in standard IPv6 behavior rather than treating them as optional or globally reachable.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
They are used for communication on the local segment only.
Why this is correct
Link-local addresses, identified by the FE80::/10 prefix, are automatically configured on every IPv6 interface and are valid only within the local network segment. A router will never forward a packet with a link-local source or destination address, so traffic using these addresses stays entirely on the local link, making this statement accurate for local-only communication.
- ✗
They are globally routable across the Internet.
Why it's wrong here
Link-local addresses are fundamentally non-routable outside their local link and are explicitly excluded from global routing tables by design. A router receiving an IPv6 packet with a link-local source or destination address will discard it rather than forward it, per RFC 4291, so these addresses cannot traverse the Internet or reach remote destinations, making the statement inaccurate.
When this WOULD be correct
If the exam question asked about the characteristics of global unicast addresses or the general routing capabilities of IPv6 addresses, then option B would be correct, as global unicast addresses are indeed routable across the Internet.
- ✓
They are commonly involved in local IPv6 neighbor interactions.
Why this is correct
IPv6 Neighbor Discovery (ND) processes, including Neighbor Solicitation and Neighbor Advertisement, rely exclusively on link-local addresses for operations such as Duplicate Address Detection (DAD), router discovery, and address resolution. Because ND messages must never leave the local link, hosts use their link-local source addresses to interact with neighboring devices, making link-local addresses essential to these local interactions.
- ✗
They exist only when DHCPv6 fails.
Why it's wrong here
Link-local addresses are not a failover mechanism that appears only after DHCPv6 fails; they are a standard and permanent feature of IPv6. Every IPv6-enabled interface generates a link-local address automatically, independent of any DHCPv6 or static address configuration, using the FE80::/10 prefix combined with an interface identifier. Even when DHCPv6 works perfectly, the link-local address remains present and operational.
When this WOULD be correct
In a question that asks about the conditions under which IPv6 link-local addresses are assigned, if it specifies that they are only assigned when DHCPv6 is not available, then option D would be correct. For example, 'What happens to IPv6 link-local address assignment when DHCPv6 is not configured?'
- ✗
They replace the need for any default gateway logic.
Why it's wrong here
Although a default gateway is typically assigned via Router Advertisement (RA) and often uses the router's link-local address, the need for default-gateway logic is not eliminated. Link-local addresses only enable communication within the local segment; for any traffic destined beyond that segment, the host must still send packets to the default gateway's link-local address, which then forwards them onward, so off-link forwarding logic remains essential.
When this WOULD be correct
If the exam question asked about the role of link-local addresses in a network where no routers exist and all devices communicate directly without a gateway, this option could be correct, as link-local addresses would be sufficient for local communication.
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.
✓They are used for communication on the local segment only.Correct answer▾
Why this is correct
Link-local addresses, identified by the FE80::/10 prefix, are automatically configured on every IPv6 interface and are valid only within the local network segment. A router will never forward a packet with a link-local source or destination address, so traffic using these addresses stays entirely on the local link, making this statement accurate for local-only communication.
✗They are globally routable across the Internet.Wrong answer — click to see why▾
Why this is wrong here
Link-local addresses have a scope of link-local (fe80::/10) and are not forwarded by routers, making them non-routable across the Internet. They are intended only for communication on a single network segment.
★ When this WOULD be the correct answer
If the exam question asked about the characteristics of global unicast addresses or the general routing capabilities of IPv6 addresses, then option B would be correct, as global unicast addresses are indeed routable across the Internet.
Why candidates choose this
Students may confuse link-local addresses with global unicast addresses, which are globally routable. The term 'address' might imply routability, but the 'link-local' scope explicitly restricts it.
✗They exist only when DHCPv6 fails.Wrong answer — click to see why▾
Why this is wrong here
Link-local addresses are automatically generated on all IPv6 interfaces regardless of DHCPv6. They are a mandatory part of IPv6 operation, not a fallback mechanism.
★ When this WOULD be the correct answer
In a question that asks about the conditions under which IPv6 link-local addresses are assigned, if it specifies that they are only assigned when DHCPv6 is not available, then option D would be correct. For example, 'What happens to IPv6 link-local address assignment when DHCPv6 is not configured?'
Why candidates choose this
Students might think link-local addresses are similar to Automatic Private IP Addressing (APIPA) in IPv4, which is used when DHCP fails. However, IPv6 link-local addresses are always present and not dependent on DHCP.
✗They replace the need for any default gateway logic.Wrong answer — click to see why▾
Why this is wrong here
For off-link communication, IPv6 hosts still require a default gateway (usually a router's link-local address) to forward packets beyond the local segment. Link-local addresses do not eliminate the need for routing logic.
★ When this WOULD be the correct answer
If the exam question asked about the role of link-local addresses in a network where no routers exist and all devices communicate directly without a gateway, this option could be correct, as link-local addresses would be sufficient for local communication.
Why candidates choose this
Since link-local addresses are used for neighbor discovery and local communication, some might incorrectly assume they handle all routing needs. However, routing to other networks still requires a gateway.
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?”
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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.