There are 2 lifetime values in DHCPv6 leases:
1) Preferred Lifetime
̶ Length of time that a valid address can be used without restrictions
̶ When the preferred-lifetime expires, the address becomes deprecated
– A deprecated address should not be used for new communications, but may continue to be used for existing communications
2) Valid Lifetime
̶ Length of time that an address remains in the valid state, during which the address can be used for existing communications
̶ When the valid-lifetime expires, the address can no longer be used
̶ valid-lifetime must be greater than or equal to the preferred-lifetime
̶ This is essentially the same as the DHCPv4 lease time
Tech Junction Answered question May 17, 2023