Final answer:
In a link-state algorithm, all routers know the complete network topology, which is maintained in the link-state database, and independently compute the shortest path to every other router. Unknown elements include delayed updates due to propagation, and routers' failures to broadcast their state, leading to potentially transiently inconsistent views of the network.
Step-by-step explanation:
In a link-state algorithm, each router has knowledge of the complete network topology. This is achieved through the periodic exchange of information with all other routers within the network; this information is broadcasted or flooded throughout the network. Each router builds a complete map of the network in the form of a graph, where nodes represent routers and edges represent the links between routers. Routers then independently calculate the shortest path to every other router using algorithms such as Dijkstra's algorithm.
What is known in the link-state algorithm is the link-state database, which contains all the information about the network topology that a router has gathered. What isn't known is the state of the network beyond the immediate broadcast domain if that information has not yet been received due to propagation delay or if some routers fail to broadcast their state due to malfunctions or misconfigurations. It is also worth noting that while all routers will eventually build a complete and accurate picture of the network's topology, there can be transient periods during which individual routers have different views of the network.