What Is Digital Subscriber Line (DSL)?
Digital Subscriber Line (DSL) is a broadband internet technology that delivers high-speed data over existing copper telephone lines. Unlike older dial-up connections, DSL allows users to access the internet while still using the phone line for voice calls at the same time.
DSL was widely adopted before cable and fiber became common and is still used today in rural or older infrastructure areas where fiber is unavailable.
For the CompTIA A+ exam, DSL is important because it represents a legacy but still relevant WAN (Wide Area Network) internet access technology that technicians may need to install, configure, or troubleshoot.
How DSL Works
Traditional telephone lines carry analog voice signals, but DSL transmits digital data at much higher frequencies than human speech.