Before and after an IPv6 address is assigned, it goes through various states. These address states are applicable to both manually and automatically configured addresses.
An IPv6 address can have one or more of the following states:
- Tentative address: An address whose uniqueness on a link is being verified. When an address is configured on a network interface (either manually or automatically), the address is initially in the tentative state. Such an address is not considered to be assigned to an interface. An interface discards received packets addressed to a tentative address, but accepts Neighbor Discovery packets related to Duplicate Address Detection (DAD) for the tentative address.
- Duplicate address: If DAD finds that an address is not unique, it is moved to the duplicate state. Such an address cannot be used for sending and receiving data.
- Preferred address: An address used to send and receive data packets from and to a network interface without any restriction on the upper layer protocols.
- Deprecated address: A preferred address becomes deprecated when its preferred lifetime expires. The use of this address is discouraged, but not prohibited.
- Valid address: A uniquely verified address that you can assign to a network interface for sending and receiving data. A valid address can be a preferred or deprecated address.
- Invalid address: A network interface address that can no longer send or receive data packets. A valid address becomes invalid when its valid lifetime expires.
An invalid address is removed from the network interface.
