The most common command used to verify a multiarea OSPF configuration is the show ip route command. Add the ospf parameter to display only OSPF-related information.
Figure 1 displays the routing table of R1. Notice how the O IA entries in the routing table identify networks learned from other areas. Specifically, O represents OSPF routes, and IA represents interarea, which means that the route originated from another area. Recall that R1 is in area 0, and the 192.168.1.0 and 192.168.2.0 subnets are connected to R3 in area 2. The [110/1295] entry in the routing table represents the administrative distance that is assigned to OSPF (110) and the total cost of the routes (cost of 1295).
Use the Syntax Checker in Figure 2 to verify the routing table of R2 and R3 using the show ip route ospf command.