Cisco CCNA (200-301)Network FundamentalsHard
A network engineer is configuring a new IPv6-enabled router. They need to ensure that the router can automatically discover neighboring IPv6 devices on the same link without manual configuration. Which IPv6 address type facilitates this discovery process?
- AGlobal Unicast Address (GUA)
- BLink-Local Address (LLA)
- CAnycast Address
- DUnique Local Address (ULA)
Show answer & explanationAnswer & explanation
Correct answer: B. Link-Local Address (LLA)
IPv6 Link-Local Addresses (LLAs) are automatically configured on every IPv6-enabled interface and are used for communication only within the local link (subnet). They are crucial for Neighbor Discovery Protocol (NDP) operations, which allow devices to discover neighbors, perform address resolution, and detect duplicate addresses without manual configuration.
Why the other options are wrong
- A. GUAs are routable globally and used for internet communication, not specifically for local link discovery.
- C. Anycast addresses are assigned to multiple interfaces and packets are routed to the nearest one, not used for neighbor discovery.
- D. ULAs are routable within an organization but not globally, and are not primarily used for local link discovery.
IPv6 Link-Local Address (LLA)
An IPv6 Link-Local Address is an automatically configured address (fe80::/10 prefix) used for communication only on the local network segment, essential for Neighbor Discovery Protocol.
- Automatically configured on every IPv6-enabled interface.
- Cannot be routed beyond the local link.
- Used by Neighbor Discovery Protocol (NDP) for local communication and discovery.
Memory trick: Link-local is like talking to your neighbor: only on your street.