PDF H12-821_V1.0 Study Guide

OSPF supports both area-level and interface-level authentication. When both are configured, interface authentication takes precedence over area authentication. This hierarchy ensures that specific interface-level configurations override the broader area-level settings when applicable ​.

If VRRP is not configured to track uplink interfaces, a failure in the master device's uplink or link will not trigger a switchover, resulting in a traffic blackhole. The VRRP mechanism relies on interface tracking to monitor connectivity and ensure role transitions upon faults. Without this configuration, no failover occurs, and traffic directed toward the master device is lost ​.

OSPF (Open Shortest Path First) mandates that the backbone area (Area 0) serves as the central area for routing information exchange. To avoid inter-area routing loops, routing information is only exchanged between the backbone area and non-backbone areas, not directly between two non-backbone areas. Consequently, each Area Border Router (ABR) must connect to the backbone area to facilitate this routing exchange ​.

The forwarding plane of a switch consists of data forwarding hardware, such as line cards or forwarding engines, and is responsible for tasks like encapsulating/decapsulating packets, providing high-speed data channels, and collecting packet statistics. However, main control boards are part of the control plane, not the forwarding plane. This distinction ensures a separation of data forwarding and control functionalities ​.