DSL stands for Digital Subscriber Line. There are two type of technologies are there Symmetric and asymmetric. For HDSL, ADSL, RADSL etc. HDSL is Symmetric. ADSL is Asymmetric. ADSL may be the most prevalent technology today but several others exist too. Asymmetric DSL technology is use in residential DSL services as home Internet users prevails use downstream bandwidth. Symmetric DSL technology is use in business-class DSL services as companies often have greater requirements for transferring data.