3.6.e Implement and troubleshoot path preference

The order of preference for OSPF routes is:

● intra-area routes, O

● inter-area routes, O IA

● external routes type 1, O E1

● external routes type 2, O E2

This rule of preference cannot be changed. However, it applies only within a single OSPF process. If a router is running more than one OSPF process, route comparison occurs. With route comparison, the metrics and administrative distances (if they have been changed) of the OSPF processes are compared. Route types are disregarded when routes supplied by two different OSPF processes are compared.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3554-3563).  . Kindle Edition.

http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/9237-9.html#intro