The Internet Systems Consortium DHCP client keeps a persistent database of leases that it has acquired that are still valid. The database is a free-form ASCII file containing one valid declaration per lease. If more than one declaration appears for a given lease, the last one in the file is used. The file is written as a log, so this is not an unusual occurrence.
The format of the lease declarations is described in dhclient.conf(5).
dhclient(8), dhcp-options(5), dhclient.conf(5), dhcpd(8), dhcpd.conf(5), RFC2132, RFC2131.
dhclient(8) Information about Internet Systems Consortium can be found at https://www.isc.org.
dhclient(8), dhclient.conf(5), dhclient-script(8).