After configuring inter-area summaries, inter-area reachability broke. Which command resolves this in a multi-area OSPF AS?

The area range command is used on an Area Border Router (ABR) to summarize routes from one OSPF area into another, typically from a non-backbone area into the backbone area (Area 0). When inter-area reachability breaks after configuring inter-area summaries, it often means that specific routes are being suppressed or not properly advertised. The area range command allows for route summarization, which reduces the size of the routing table and improves scalability, but it must be configured correctly on the ABRs that connect the areas. Configuring area range on an ASBR (Autonomous System Border Router) is incorrect because ASBRs summarize external routes into OSPF, not inter-area routes. The summary-address command is used on an ASBR to summarize external routes being injected into OSPF, not for inter-area summarization between OSPF areas.