The valid_lft (valid lifetime) signifies the duration for which an IP address is considered valid and can be used by the network interface. It is part of the output when you check network interfaces using commands like ip addr or ip a.
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Value: The value indicates the time in seconds that the IP address will remain valid. If it shows
forever, it means the IP address does not have a defined expiration time and can be used indefinitely. -
Purpose: This is particularly relevant in dynamic IP address assignments, such as those obtained via DHCP (Dynamic Host Configuration Protocol), where IP addresses may have a limited validity period before they need to be renewed or released.
In summary, valid_lft helps in understanding how long an IP address can be used before it may need to be refreshed or replaced.
