An address resolver system that assists a node in an IPv6 network to select an address for connectivity with a node in an IPv4 network when both DSTM and NAT-PT transition mechanisms are available. Native connectivity can be achieved by preferring an encapsulation or tunnelling mechanism such as DSTM where possible over a translation mechanism such as NAT-PT. A range of encapsulation and translation mechanisms are envisaged. The resolver determines capabilities of the node and of the application that requires the address in order to make the selection.
