The Vault seal configuration can be set in two ways: through the Vault configuration file or through environment variables. The Vault configuration file is a text file that contains the settings and options for Vault, such as the storage backend, the listener, the telemetry, and the seal. The seal stanza in the configuration file specifies the seal type and the parameters to use for additional data protection, such as using HSM or Cloud KMS solutions to encrypt and decrypt the root key. The seal configuration can also be set through environment variables, which will take precedence over the values in the configuration file. The environment variables are prefixed with VAULT_SEAL_ and followed by the seal type and the parameter name. For example, VAULT_SEAL_AWSKMS_REGION sets the region for the AWS KMS seal. References: Seals - Configuration | Vault | HashiCorp Developer, Environment Variables | Vault | HashiCorp Developer

Vault supports CIDR-bound tokens, which are tokens that can only be used from a specific set of IP addresses or network ranges. This is a way to limit the scope and exposure of a token in case it is compromised or leaked. CIDR-bound tokens can be created by specifying the bound_cidr_list parameter when creating or updating a token role, or by using the -bound-cidr option when creating a token using the vault token create command. CIDR-bound tokens can also be created by some auth methods, such as AWS or Kubernetes, that can automatically bind the tokens to the source IP or network of the client. References: Token - Auth Methods
| Vault | HashiCorp Developer, vault token create - Command | Vault | HashiCorp Developer

Comprehensive and Detailed In-Depth Explanation:
In HashiCorp Vault, thedefault TTL (Time To Live)for tokens, when not explicitly specified, is768 hours, equivalent to32 days. This applies to both the initial TTL and the maximum TTL unless overridden.
* Default Configuration: The documentation states: "When no specific TTL is provided, a generated token will inherit the default TTL which is 768 hours (32 days)." This long default ensures usability in many scenarios while allowing customization.
* Customization Option: Operators can adjust this using commands like vault write sys/mounts/auth
/token/tune default_lease_ttl=1h max_lease_ttl=24h, but without such tuning, 768 hours applies.
* Incorrect Options:
* A. 24 hours: Too short for Vault's default; it's a common custom setting instead.
* B. 15 minutes: Far too brief and not aligned with Vault's defaults.
* D. 60 minutes: Another common custom value, not the default.
This default balances usability with security, encouraging explicit configuration for shorter-lived tokens when needed.
Reference:https://developer.hashicorp.com/vault/docs/concepts/tokens

Vault Agent is a client daemon that provides the following features:
* Auto-Auth - Automatically authenticate to Vault and manage the token renewal process for locally- retrieved dynamic secrets.
* API Proxy - Allows Vault Agent to act as a proxy for Vault's API, optionally using (or forcing the use of) the Auto-Auth token.
* Caching - Allows client-side caching of responses containing newly created tokens and responses containing leased secrets generated off of these newly created tokens. The agent also manages the renewals of the cached tokens and leases.
* Templating - Allows rendering of user-supplied templates by Vault Agent, using the token generated by the Auto-Auth step.
* Process Supervisor Mode - Runs a child process with Vault secrets injected as environment variables.
One of the benefits of using the Vault Agent is that it will manage the lifecycle of cached tokens and leases automatically. This means that the agent will handle the token renewal and revocation logic, as well as the lease renewal and revocation logic for the secrets that are cached by the agent. This reduces the burden on the application developers and operators, and ensures that the tokens and secrets are always valid and up-to-date.
References: Vault Agent | Vault | HashiCorp Developer, Caching - Vault Agent | Vault | HashiCorp Developer

Comprehensive and Detailed In-Depth Explanation:
Vault policies define access control using specific capabilities. The Vault documentation lists the valid capabilities:
"When creating a policy, only the following capabilities are available in Vault:
* create
* read
* update
* delete
* list
* sudo
* deny"-Vault Policies: Capabilities
* A: list is valid:
"The list capability enables the user to view a list of available resources or entities within Vault."
-Vault Policies: Capabilities
* B: deny is valid:
"The deny capability is used to explicitly deny access to specific resources or operations within Vault."
-Vault Policies: Capabilities
* E: create is valid:
"The create capability allows the user to create new policies, roles, tokens, and other entities within Vault."
-Vault Policies: Capabilities
* F: write is a common shorthand for update in Vault's context and is valid:
"The update capability (often referred to as write in CLI contexts) allows the user to modify or update existing resources or entities within Vault."
-Vault Policies: Capabilities
Note: While write isn't explicitly listed, it's synonymous with update in practice, as confirmed by CLI usage and community convention.
* C: apply is not a Vault policy capability.
* D: root is not a capability; it's a policy name for superuser access.
References:
Vault Policies: Capabilities