Comprehensive and Detailed in Depth Explanation:

Vault tokens have a Time-To-Live (TTL) that determines their expiration time, after which they are revoked. Parent-child relationships mean that revoking a parent token also revokes its children, regardless of their TTLs. Let’s analyze:

A: TTL 4 hours- Expires after 4 hours, no children listed.

B: TTL 6 hours- Expires after 6 hours, parent to C.

C: TTL 4 hours (child of B)- Expires after 4 hours or if B is revoked earlier.

D: TTL 3 hours- Expires after 3 hours, parent to E.

E: TTL 5 hours (child of D)- Expires after 5 hours or if D is revoked earlier.

Analysis:

Shortest TTL is D (3 hours), so it expires first unless a parent above it (none listed) is revoked sooner.

E (5 hours) is a child of D. If D is revoked at 3 hours, E is also revoked, despite its longer TTL.

A and C (4 hours) expire after D.

B (6 hours) expires last among parents.

The question asks which token(s) are revoked first based on TTL alone, not manual revocation. D has the shortest TTL (3 hours) and will be revoked first. E’s revocation depends on D, but the question focuses on initial expiration. Thus, only D is revoked first based on its TTL.

Overall Explanation from Vault Docs:

Tokens form a hierarchy where child tokens inherit revocation from their parents. “When a parent token is revoked, all of its child tokens—and all of their leases—are revoked as well.” TTL dictates automatic expiration unless overridden by manual revocation or parent revocation. Here, D’s 3-hour TTL is the shortest, making it the first to expire naturally.