A discussion of the operational characteristics of the various adaptive routing techniques. The Memorandum shows that the techniques previously investigated are insufficient for the task, and investigates a number of promising alternatives. Among these are some stochastic techniques that use information on messages passing through the network to adjust the tables, and some deterministic techniques that use dynamic programming or graph-theoretic algorithms to recalculate changes in the tables from observed changes in the network. Each alternative has operational advantages for certain communications systems, and certain disadvantages for others. The appropriate techniques or combinations of techniques depend on several enumerated factors. The authors point out a number of research areas where further efforts in the analysis and simulation of such techniques will be useful in the design of future distributed communications systems.