In this paper we shall consider the nonlinear delay differential equation (equation omitted) where m is a positive integer, ${eta}$(t) and $delta$(t) are positive periodic functions of period $omega$. In the nondelay case we shall show that (*) has a unique positive periodic solution (equation omitted), and show that (equation omitted) is a global attractor all other positive solutions. In the delay case we shall present sufficient conditions for the oscillation of all positive solutions of (*) about (equation omitted), and establish sufficient conditions for the global attractivity of (equation omitted). Our results extend and improve the well known results in the autonomous case.