A.
The i su 10.1.0.0/23 route is a suppressed route.
B.
The i su 10.1. 0.0/23 route is a summary route.
C.
The i su 10.1.0.0/23 route is an IS - IS external route.
D.
The R1 IS - IS router is an ASBR.
E.
The R1 IS - IS router is an ABR that belongs to multiple IS - IS areas.
F.
The R1 IS - IS router is performing route aggregation and is suppressing the more specific 10.1.0.0/23 prefix.