Cisco Certified Network Professional Practice Test

During an Adjacency Drop, packets experience a complete failure to forward through the network. This situation arises in the context of routing protocols and network layers where the state of the adjacency between routers is critical for packet forwarding. When an adjacency is dropped, the routers involved can no longer effectively communicate or share their routing information, leading to the inability to forward packets towards their intended destination. In essence, when a router loses adjacency with its neighbor, it may be operating under the assumption that the routes to which it was previously connected are now invalid or unavailable. This results in the router dropping packets destined for those routes entirely, as it has no reliable next-hop information to forward them onward. This behavior contrasts with other scenarios where packets may still be forwarded (though potentially incorrectly, such as in a routing loop) or where packets are sent back to the sender due to other types of errors or issues in the network. In the case of an Adjacency Drop, the critical element is the total loss of forward path knowledge, resulting in packets failing to move through the network entirely.