Table 1: Comparative table. "Pair with": The remote Keep-Alive that this Keep-Alive can be paired with. The numbers refer to the serial numbers in the first column. "UDP?": Whether this Keep-Alive works unchanged with UDP (assuming it is properly paired with another Keep-Alive). "Load?": Whether this Keep-Alive creates network load in the normal condition; that is, when the connection is functioning and significant two-way traffic is passing over the connection. Piggybacking may reduce these loads. Also, even where there is a load, it may be insignificant. (*NullKeepAlive does nothing; it is a placeholder along the lines of the "Null Object" design pattern.)
