Catalyzes the initial step in the synthesis of dolichol-P-P-oligosaccharides. a dolichyl phosphate + UDP-N-acetyl-alpha-D-glucosamine = N-acetyl-alpha-D-glucosaminyl-diphosphodolichol + UMP Inhibited by tunicamycin. Protein modification; protein glycosylation. Belongs to the glycosyltransferase 4 family.