isc-dhcp-client-ddns - 4.4.1-2+deb10u1 main

This a Dynamic DNS enabled version of the DHCP client.
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Dynamic Host Configuration Protocol (DHCP) is a protocol like BOOTP
(actually dhcpd includes much of the functionality of bootpd). It
gives client machines "leases" for IP addresses and can
automatically set their network configuration. If your machine
depends on DHCP (especially likely if it's a workstation on a large
network, or a laptop, or attached to a cable modem), keep this or
another DHCP client installed.
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Extra documentation can be found in the package isc-dhcp-common.