Nearly all ISPs assign addresses to dialup and cable modem customers using DHCP.To keep up, DNS needed to support the dynamic addition and deletion of records.If the name server receiving an authorized update message is not the primary master for the zone, it forwards the update "upstream" to its master server, a process referred to as "update forwarding." If this next server, in turn, is a slave for the zone, it also forwards the update upstream.
An updater can find the authoritative name servers for a zone by retrieving the zone's NS records.
Sorry, I forgot to put in the question that these are static IP's.
I realize I could add the DNS entries on the Windows side manually as well, but I'm not actually in charge of that Windows DNS server.
However, many home users are assigned an IP address that changes more frequently. This makes it a challenge to translate a Name to one of these IP addresses.
These Dynamic DNS services allow the user to choose a hostname and set an initial IP address to correspond to that hostname.