ILOG CPLEX 11.0 User's Manual > Advanced Programming Techniques > Advanced MIP Control Interface > Node Selection Callback

The user can influence the order in which nodes are explored by installing a node selection callback (through CPXsetnodecallbackfunc). When CPLEX chooses the node to explore next, it will call the user callback routine, with CPLEX's choice as an argument. The callback has the option of modifying this choice.