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The accumulation of free and backup DHCPv4 leases; and free, expired, and released DHCPv6 leases results in unnecessary growth of database objects. The DHCP lease scavenging feature enables member DHCP servers to automatically delete free and backup IPv4 leases; and free, expired, and released IPv6 leases that remain in the database beyond the specified period of time, thus reducing the number of database objects.
When you enable this feature for DHCPv4 leases, the appliance permanently deletes the free and backup IPv4 leases, and you can no longer view or retrieve the lease information. This option can be enabled globally at the Grid level, and more specifically for a member, shared network, network, network container, DHCP range, network template, DHCP range template.
When you enable this feature for DHCPv6 leases, the appliance permanently deletes the free, expired, and released IPv6 leases, and you can no longer view or retrieve the lease information. This option can be enabled at the Grid level, and overridden at the member level.
The period of time that you specify is the duration after the expiration date of a lease, not its release date. For example, you specify a time period of 5 days when you enable this feature. If the lease time of an IP address is 10 days, but the lease is released after five days, the appliance still deletes the lease from the database after 15 days because the IP address has been leased.
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Note: If you plan to enable this feature after upgrading from a previous NIOS version, Infoblox recommends that you enable it during off-peak hours, as it may impact DHCP services.
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