Valid lifetime

The valid lifetime, which is the total time the address is available, is equal to or greater than the preferred lifetime. The valid lifetime enables communication to continue for transactions that began before the address became deprecated. However, in this time frame, the address should no longer be used for new communications. If this time expires without the deprecated address being refreshed, the address becomes invalid and might be assigned to another interface.

IPv6 unicast addresses lifetimes

Address source

Lifetime criteria



Statically configured unicast


Autoconfigured global

Finite preferred and valid lifetimes


Finite preferred and valid lifetimes

A new, preferred address used as a replacement for a deprecated address can be acquired from a manual, DHCPv6, or autoconfiguration source.