What is the fastest speed that DSL connections can get ?
This is a complex question that depends on the DSL technology used, your actual distance to the telco, as well as the service provider.
Typical residential ADSL services in the US currently offer speeds of up to 6.0 Mbits/s downstream. That maximum speed depends on the ISP cap, and may vary depending on distance to the telco.
The newest ADSL2+ standard provides for up to 24Mbit/s downstream, 1Mbit/s upstream bandwidth.
VDSL2 can offer speeds of up to 100 Mbit/s downstream and is offered in some Asian and European countries as well.
See also: ADSL Annex standards