When configuring IPv4 and IPv6 IS-IS routing on Cisco IOS XR routers, which three statements are correct? (Choose three.)
A. By default, a single SPF is used for both IPv4 and IPv6, so the IPv4 and IPv6 topology should be the same.
B. By default, the IS-IS router type is Level 1 and Level 2.
C. All IS-IS routers within the same IS-IS area must be configured with the same IS-IS routing process instance ID.
D. By default, metric-style narro w is used.
E. By default, the IS-IS interface circuit type is Level 1 and Level 2.
F. The area IS-IS address-family configuration command is used to specify the IS-IS area address.
