Comprehensive and Detailed Step-by-Step Explanation:
OSPF Route Preference Hierarchy:
OSPF uses the following preference order for route types when the prefix is the same:
Intra-area routes (D): Routes within the same OSPF area have the highest priority.
Inter-area routes (B): Routes between different OSPF areas are preferred after intra-area routes.
Type 1 external routes (A): External routes redistributed into OSPF, considering the internal OSPF cost to the ASBR.
Type 2 external routes (C): External routes redistributed into OSPF, ignoring the internal OSPF cost to the ASBR.
Lowest Priority:
Type 2 external routes (C) are given the lowest priority because they represent external information that does not consider internal OSPF costs.
References:
HCIA-Datacom Study Guide, Chapter: OSPF Route Preference
Huawei OSPF Routing Table Selection Rules