In this paper, we study finite groups all of whose nontrivial normal subgroups have the same order. In the solvable case, the groups are determined. In the insolvable case, some characterizations are given.
In this paper, we study finite groups all of whose nontrivial normal subgroups have the same order. In the solvable case, the groups are determined. In the insolvable case, some characterizations are given.