A computer’s Internet Protocol address (IP address) is the numerical address of that computer. The Internet Protocol (IP) recognizes a specific machine by this address. An IP address consists of four groups of decimal digits separated by periods, for example 74.50.16.248. Each of the four groups is an 8 bit number that ranges from 0 to 255.

To avoid conflicts, each IP address on any given network must be unique. An IP address can be assigned manually or automatically. Typically, IP addresses will be assigned by BOOTP or DHCP servers. However, if Windows is unable to detect either server, it will assign the computer an IP address using APIPA. In this case, OPC will not usually work.

Windows uses Address Resolution Protocol (ARP) to assign an IP address to a computers Media Access Control address (MAC address).

DNS (Domain Name System) Servers enable IP addresses to be “translated” to a human-friendly format, called a host name, such as www.opcti.com.

Most OPC applications will accept an IP address instead of a host name to specify the address of the remote computer. Since DCOM communication depends on a well working TCP/IP backbone, the IP address has in important role in ensuring proper communication.

See also ARP, BOOTP, DCOM, DHCP, DNS, Internet Protocol