IP address
An IP address serves two principal functions. It identifies the host, or more specifically its network interface, and it provides the location of the host in the network, and thus the capability of establishing a path to that host. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."
The header of each IP packet contains the IP address of the sending host, and that of the destination host.
Inter-domain
Inter-domain is data flow control and interaction between Primary Domain Controller (PDC) computers. This type of computer uses various computer protocols and services to operate. It is most commonly used to multicast between internet domains.
An Internet service provider, ISP, is provided with a unique URL access address. This address is a unique number. The number for each ISP is stored within a DNS server. The DNS servers interpret the ISP URL Domain name and provide the appropriate IP address number. The Domain is under the control of a specialised computer, called a PDC, (primary domain controller). This computer holds records of all the user accounts within the domain, their rights to access information, and lists of approved System Operatives. This PDC is backed up by a SDC, (a secondary domain controller), this computer synchronises itself with the PDC and takes over the role in the event of a PDC failure. Multiple replication servers connect to these control computers and they are routed to the Internet backbone to provide the requested data to and from the domain. 
Internet protocols that are focused on inter-domain functions include: Border Gateway Multicast Protocol, Classless Inter-Domain Routing, Multicast Source Discovery Protocol, and Protocol Independent Multicast.
A PDC uses a number of special computer programs to announce its presence to other domain controllers. It uses Windows Internet naming service WINS and Browser services to allow other computers to gain access to digital information that it has control over.