Technical explanation
The question’s “12 Announcements” wording is a source transcription error for L2 Announcements . This feature makes Kubernetes Services visible and reachable to clients on the local Layer 2 network, particularly in on-premises, office, campus, or bare-metal environments that do not use BGP-based service advertisement.
Cilium responds to ARP requests for IPv4 Service addresses and NDP requests for IPv6 addresses. A selected node advertises the LoadBalancer IP or ExternalIP using its MAC address and receives traffic for that virtual IP. Cilium then applies its service load-balancing functionality to forward the connection to an appropriate backend. Leadership is coordinated so that one node advertises a given Service at a time, and the virtual IP can move to another eligible node after failure.
The feature is not intended to provide general Layer 2 multicast, making A incorrect. DNS service discovery is handled through Kubernetes DNS and is independent of L2 announcements, eliminating C. It also does not define Layer 2 security policies, so D is incorrect.
Thus, the purpose is external Service reachability on the local area network, exactly as described by B.
Official references
L2 Announcements .
Study Guide topic: BGP and External Networking.
