Based on the show ip route isis output on R1, which statement is true?

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.

Explanation:

When viewing the “show IP route ISIS” output, the “su” entry represents a summarized route.
This is the direct result of the “summary-address” router configuration command. When
creating the summary route. The Cisco IOS automatically creates the summary route and
point it to interface Null 0.