Refer to the exhibit. An architect is designing an ISIS network for a customer migrating from IPv4 to IPv6. The current network uses narrow metrics, and the IPv6 areas will increase to 10 within the…

Enabling `metric-style transition` on core routers C1 and C2 is crucial for a graceful migration from narrow to wide ISIS metrics. This allows both metric styles to be advertised simultaneously, facilitating a smooth transition across the ISIS domain.

While `metric-style transition` should ideally be enabled on all ISIS routers for a complete domain-wide migration, selecting 'all routers' as a single solution doesn't satisfy the 'choose two' requirement, and C1/C2 represent key backbone points for this transition.

While edge routers E1 and E2 may eventually need MT-ISIS for IPv6, enabling it on the core or backbone routers (C1/C2) is more fundamental for ensuring network-wide IPv6 routing and preventing blackholing during migration.

Multi-Topology ISIS (MT-ISIS) is essential for running independent routing topologies for IPv4 and IPv6. Enabling `multi-topology` under `address-family ipv6` on core routers C1 and C2 ensures IPv6 routing is correctly established and prevents IPv6 traffic from being blackholed in the IPv4 network during migration.

Enabling `metric-style transition` only on edge routers E1 and E2 is a partial application and less impactful for the overall backbone metric transition compared to enabling it on core routers C1 and C2.