Which Designated Intermediate System selection option is valid when deploying IS-IS in a broadcast medium that connects two networking devices as a point-to-point network type?

IS-IS point-to-point network types do not use a pseudonode and therefore have no DIS election process. When a broadcast medium is explicitly configured as point-to-point using 'isis network point-to-point', the two routers form a direct adjacency without a designated system, eliminating the DIS selection entirely and also skipping CSNP flooding used on broadcast segments.

DIS selection on broadcast IS-IS networks uses interface priority (not IP address) as the primary criterion, and this entire process is bypassed on point-to-point types.

The router with the highest (not lowest) priority wins DIS election on broadcast networks, and priority is irrelevant on point-to-point types.

Loopback IP addresses play no role in IS-IS DIS election under any network type; the criteria are interface priority and MAC address.

The lowest MAC address is used as a tiebreaker on broadcast networks when priorities are equal, but no such election occurs on point-to-point network types.