Comprehensive and Detailed In-Depth Explanation:

The Transit secrets engine encrypts data without local key storage. The Vault documentation states:

" The Transit secrets engine allows you to send cleartext data to Vault to be encrypted. Vault will encrypt the data with the referenced encryption key, which is stored locally, and returns the ciphertext to the application. Although the encryption keys in the Transit secrets engine are exportable, they are generally kept in Vault. "

— Transit Tutorial

C : Correct. Meets encryption and key security needs:

" It allows applications to encrypt data before storing it in a backend database and decrypt it when needed, without storing encryption keys locally. "

— Vault Secrets: Transit

A : PKI is for certificates.

B : SSH is for SSH credentials.

D : Cubbyhole is for temporary storage.

Comprehensive and Detailed In-Depth Explanation:

To revoke all secrets from the database/ engine, use vault lease revoke -prefix. The Vault documentation states:

" If you need to revoke many leases, you can use vault lease revoke -prefix < prefix > and Vault will revoke all leases associated with the specified path. For example, you can revoke all leases associated with an entire database secrets engine by using vault lease revoke -prefix database/. "

— Vault Commands: lease revoke

D : Correct. Revokes all leases under database/:

" Using the command vault lease revoke -prefix database/ will revoke all the leases that have a prefix matching the specified path database/. "

— Vault Commands: lease revoke

A : Revokes tokens, not leases.

B : Disables the engine, not existing secrets.

C : Renews a specific lease, not revokes all.

Comprehensive and Detailed In-Depth Explanation:

Dynamic credentials have a lease with a TTL, after which Vault revokes them. To extend their validity, you renew the lease. The Vault documentation states:

" If a lease has been created in Vault, it has an associated TTL in which it will expire and be revoked. If the lease needs to be extended for some reason, you can use the command vault lease renew < lease_id > to extend the TTL of the lease so it will not expire at its original TTL and will be extended by the time specified in seconds from the current time the lease renewal was issued. "

— Vault Commands: lease renew

A : Correct. Renewing the lease (e.g., vault lease renew < lease_id > ) extends the TTL:

" Renewing the lease of the dynamic credentials in Vault allows you to extend the validity period without having to generate new credentials. "

— Vault Commands: lease renew

B : Generating a new lease creates new credentials, disrupting the query.

C : Creating a new role doesn’t extend existing credentials’ TTL.

D : Revoking the lease terminates the credentials, halting the query.