Which three options are IS-IS design considerations when connecting two Layer 3 switches directly using a 10 GBASE-T cabling and formatting an IS-IS neighbor adjacency?

The default IS-IS network type on Ethernet is broadcast, not point-to-point, so a DIS is elected; point-to-point mode must be explicitly configured with 'isis network point-to-point'.

This choice is a truncated or factually incomplete variant of choice F and does not correctly describe the full DIS preemption condition.

IS-IS adjacency requires that area addresses, IS-IS levels (L1, L2, or L1-2), and interface MTU all match between neighbors; a mismatch in any of these prevents adjacency formation and the System ID must be unique per router within the domain.

Lowering IS-IS hello and dead timers directly increases the rate of hello packet generation, consuming additional bandwidth and CPU cycles, and if set too aggressively can cause flapping adjacencies and network instability.

This statement advocates tuning timers as fast as possible without acknowledging the bandwidth and CPU cost trade-off covered in choice D, making it an incomplete and potentially harmful design guideline.

On Ethernet, IS-IS operates in broadcast mode and elects a DIS; unlike OSPF DR/BDR, DIS election is fully preemptive - a router with a higher interface priority or, on a tie, a higher MAC address will immediately take over the DIS role from the current holder.

IS-IS does not require hello timers to match between neighbors; each router derives the hold time from the hello interval advertised in the peer's IIH, allowing asymmetric timer configurations.