This reports the specific egress interface for the adjacency forwarding element in this list, reading zero if the list contains no adjacency forwarding element. This lets an admin directly identify which physical or logical interface a given prefix's traffic actually egresses through, without needing to separately cross-reference the adjacency table, which is useful when auditing whether traffic to a critical prefix is using the expected primary link versus an unexpected backup path. An admin verifying failover behavior could check this object before and after a primary link failure to confirm traffic to a monitored prefix shifted from the primary interface's index to the backup interface's index as expected.