Brijesh,
I opened your drawing and did some tests.
1.] In the drawing drawing_units option is set to mm
2.] I exported t001979_mm.dxf file and opened it in CR2 M030 without problems (File > Save a Copy > select DXF format > use default setting for ACAD 2007 format)
3.] Your DXF file does not contain drawing format, it contains only 1 rectangle. How did you create this DXF file ?
Martin Hanak