This document contains solutions to questions about data communications techniques. It discusses topics like digital modulation techniques, data rates for different modulation schemes, synchronous time-division multiplexing (TDM) concepts and calculations, and transmission media characteristics. Sample questions are provided about amplitude modulation (AM), phase modulation (PM), frequency-division multiplexing (FDM), transmission media like twisted-pair cable and coaxial cable, and network switching techniques like circuit switching, packet switching and frame switching.