Refer to the exhibit. CSRV1 must redistribute OMP routes into OSPF Area 1 that must be seen as type 7 LSA by RTR1. CSRV1 must also advertise the default route toward RTR1, which is learned via OMP…

'area 1 stub no-summary' configures Area 1 as a totally stubby area, which blocks all external LSAs and does not support type 7 LSAs that NSSA requires.

'default-information originate always' injects a type 5 (external) LSA default route into normal OSPF areas, but type 5 LSAs are not flooded into NSSA - only type 7 LSAs are valid inside NSSA.

The 'area 1 nssa default-information-originate' command configures Area 1 as a Not-So-Stubby Area and automatically injects a type 7 LSA default route toward RTR1, satisfying both the NSSA and default route requirements simultaneously.

The 'redistribute omp subnets' command is required to import OMP-learned routes into the OSPF process; without the 'subnets' keyword, only classful networks are redistributed, causing subnetted routes to be dropped.

'area 1 nssa no-summary' creates a totally NSSA (blocking inter-area summary LSAs) but does not automatically originate a default route toward the NSSA, leaving RTR1 without a default.