Dynamic secrets are generated on-demand by Vault and have a limited time-to-live (TTL). They do not ensure that administrators can see every password used, as they are often encrypted and ephemeral. The benefits of dynamic secrets are:
They support systems that do not natively provide a method of expiring credentials, such as databases, cloud providers, SSH, etc. Vault can revoke the credentials when they are no longer needed or when the lease expires.
They minimize the damage of credentials leaking, as they are short-lived and can be easily rotated or revoked. If a credential is compromised, the attacker has a limited window of opportunity to use it before it becomes invalid.
They replace cumbersome password rotation tools and practices, as Vault can handle the generation and revocation of credentials automatically and securely. This reduces the operational overhead and complexity of managing secrets.

The Transit secrets engine supports the rotation of encryption keys, which allows you to change the key that is used to encrypt new data without affecting the ability to decrypt data that was already encrypted. This reduces the amount of content encrypted with a single key in case the key gets compromised, and also helps you comply with the NIST guidelines for key rotation. You can rotate the encryption key manually by invoking the /transit/keys/<name>/rotate endpoint, or you can configure the key to automatically rotate based on a time interval or a number of encryption operations. When you rotate a key, Vault generates a new key version and increments the key's latest_version metadata. The new key version becomes the encryption key used for encrypting any new data. The previous key versions are still available for decrypting the existing data, unless you specify a minimum decryption version to archive the old key versions. You can also delete or disable old key versions if you want to revoke access to the data encrypted with those versions. Reference: https://developer.hashicorp.com/vault/docs/secrets/transit1, https://developer.hashicorp.com/vault/api-docs/secret/transit2

The CLI command vault login -method ldap username=mitchellh generates a token that is response wrapped. This means that the token contains a base64-encoded response wrapper, which is a JSON object that contains information about the token, such as its policies, metadata, and expiration time. The response wrapper is used to verify the authenticity and integrity of the token, and to prevent replay attacks. The response wrapper also allows Vault to automatically renew the token when it expires, or to revoke it if it is compromised. The -method ldap option specifies that the authentication method is LDAP, which requires a username and password to be provided. The username mitchellh is an example of an LDAP user name, and the password will be hidden when entered. Reference: Vault CLI Reference | Vault | HashiCorp Developer, Vault CLI Reference | Vault | HashiCorp Developer

An identity group is a collection of entities that share some common attributes. An identity group can have one or more policies attached to it, which are inherited by all the members of the group. An identity group can also have subgroups, which can further refine the policies and attributes for a subset of entities.
One of the use cases of an identity group is to consistently apply the same set of policies to a collection of entities. For example, an organization may have different teams or departments, such as engineering, sales, or marketing. Each team may have its own identity group, with policies that grant access to the secrets and resources that are relevant to their work. By creating an identity group for each team, the organization can ensure that the entities belonging to each team have the same level of access and permissions, regardless of which authentication method they use to log in to Vault. Reference: Identity: entities and groups | Vault | HashiCorp Developer, vault_identity_group | Resources | hashicorp/vault | Terraform | Terraform Registry

The maximum time-to-live (TTL) for a token is defined by the lowest value among the following factors:
The authentication method that issued the token. Each auth method can have a default and a maximum TTL for the tokens it generates. These values can be configured by the auth method's mount options or by the auth method's specific endpoints.
The mount endpoint configuration that the token is accessing. Each secrets engine can have a default and a maximum TTL for the leases it grants. These values can be configured by the secrets engine's mount options or by the secrets engine's specific endpoints.
A parent token TTL. If a token is created by another token, it inherits the remaining TTL of its parent token, unless the parent token has an infinite TTL (such as the root token). A child token cannot outlive its parent token.
System max TTL. This is a global limit for all tokens and leases in Vault. It can be configured by the system backend's max_lease_ttl option.
The client system that uses the token cannot define the maximum TTL for the token, as this is determined by Vault's configuration and policies. The client system can only request a specific TTL for the token, but this request is subject to the limits imposed by the factors above.