Method and apparatus for generating replies to address resolution protocol requests

The invention relates generally to the field of networking. More specifically, it relates to the use of the Address Resolution Protocol (ARP) and to ensuring that only a single and consistent reply is generated in response to each ARP request. The invention ensures that a single and consistent reply is made to ARP request in a system of connected IP networks. In each host, the first adapter A to become active is designated as being in an arbitrary first physical network (PNET). For each subsequent adapter B to become active on a host, the host sends a packet over one of the adapters (A) of each network already known to the host with a hop count of one. If the packet is received over adapter B, it is known that adapters A and B are in the same physical network. If this occurs, adapter B is marked as being in the same network PNETas adapter A. If the packet is not received over adapter B then B is in a different physical network as A. In this event, adapter B is marked as being in a new network PNET. When adapter A becomes inactive, if there are other active adapters in the physical network to which A belongs, then one of the remaining adapters B in that physical network is designated to have the responsibility for replying to ARP requests for A. A gratuitous ARP advertisement is transmitted into the network mapping IP-A with MAC-B. When adapter A again becomes active, adapter A will re-assume ownership of ARP replies for IP address A.