This is the only question for this section. Some ISPs place restrictions on which computers are allowed to get an IP address from their DHCP server(s). Those systems work by requiring your computer to prove it is authorized to get an address by supplying a special name. If your ISP requires this, then enter the name they provided to you here. Most ISPs no longer need this. At one time, the now defunct @Home network which managed my cable company's network did things this way. I no longer use cable, but have switched to a business class DSL connection which does not need this.
NOTE: When using DHCP, other network settings such as the IP address, default gateway, netmask and DNS name server address are provided automatically during system startup. This is now very common and the preferred way for network administrators to manage their IP addresses.