What type of information do Type 4 LSA advertisements primarily provide?

Type 4 LSA (Link State Advertisement) advertisements primarily convey information about Network Layer Reachability Information (NLRI) in OSPF (Open Shortest Path First) routing protocols. Specifically, they provide details about the routes to Autonomous System Border Routers (ABRs) and their associated summary routes. The purpose of Type 4 LSAs is to facilitate inter-area routing by informing the routers within one area about the exit points to other areas of the OSPF domain.

By distributing this information, Type 4 LSAs enable routers to make informed decisions when routing packets that need to traverse different areas within the OSPF network. This is crucial for maintaining efficient routing as it allows routers in one area to understand how to reach networks that are located in different areas via the ABRs.

The other answer choices do not align with the specific function of Type 4 LSAs. Router configurations and performance metrics pertain to the operational parameters and efficiency of routers but are not directly related to the summaries provided by Type 4 LSAs. Similarly, error states of network links fall outside of the scope of the information conveyed by these LSAs, which focus on routing reachability rather than diagnostic or state messages regarding link health.