An IP lease ensures the recovery ofunused IP addresses to the pool of available IP addresses. The time limitensures that the host is still alive and connected to the network. Scavengingis the process by which a DNS server will purge stale record. The server setsthe span of time for which it considers a record stale.
It then will remove therecord to prevent multiple hostnames pointing to the same IP address. Theoption “Obtain an IP address automatically” sets the network interface toobtain its IP address, gateway, and DNS server from a DHCP server. DHCP and DNS are two systems thatrequire integration to prevent IP collisions. When the DHCP server changes theIP address of a host it must update the associated DNS record to sure proper nameresolution. This accomplished through dynamic updating of the DNS server. Theprocess used to accomplish this depends on the setup.
A DHCP server can sendthe update or the client itself can send the update or the PTR/A records.Dynamic DNS is more commonly talked about when registering a Domain name with adynamic IP address. This can be accomplished through software that sits on arouter or host and send a DNS server the current IP address of the network.