Let G be a finite group and N(G) be its norm. Then N(G) is a characteristic subgroup of G which normalizes every subgroup of G. In this paper, we will study the structure of G under one of the following conditions: 1) norm quotient group G/N(G) is cyclic; 2) all Sylow subgroups of G/N(G) are cyclic and in particular if the order of G/N...