From time to time I get asked that very question by my clients or people who know me and therefore I am taking the opportunity to outline the two methodologies used to achieve physical connection to the Internet. First of all, both technologies known as Broadband offer high-speed Internet access compared to the dialup rarely-used-nowadays access.

These two technologies open up homes and small businesses to a new realm of possibilities for network connectivity and applications. Video-on-demand, multimedia conferencing, and online gaming are just a few examples of services on the Internet that don't work so well using dialup of 56 Kbps speed but can function nicely at broadband data rates.

For definition, ADSL stands for Asynchronous Digital Subscriber Line which means your internet connection speed for the download is different (higher) than the upload. Most Internet users fit this criteria unless they are into video conferencing, IP Telephony or hosting large web-databases. SHDSL (Synchronous High-Definition Subscriber Line) is the answer for the latter usage were download and upload speeds are the same.

ADSL uses the same telephone line were your service provide once you subscribe with, activate your telephone line for ADSL connection pending service availability of course (their nearest ADSL-enabled exchange centre needs to be under 4.1 KM from your location otherwise dropouts may be experienced). The telephone line will be split into two different frequency channels one, low frequency (40-50MHz) used for sound and the other (300MHz) for Data. You will be always connected to the Internet, no more dialups and can use your telephone or fax while browsing the Internet. This often is referred to as ADSL piggy-back onto your telephone line.

Cable modem uses a shared cable line to provide service to an entire neighbourhood. Basically, all cable modem customers in the neighbourhood belong to the same local area network (LAN). Without any security measures in place, anybody in the neighbourhood might technically be able to click on their Windows Network Neighbourhood icon and actually see the computer names and addresses of their neighbours on the service. Try to uncheck the File and Printer sharing option if you do not need it and/or implement some basic firewall restrictions.

ADSL uses dedicated rather than shared cabling however, once you go past your ISP (Internet Service Provider) system then you are part of one big shared network which is the Internet and that fact applies to both ADSL and Cable Modem. With Cable Modem technology, once the ISP technician installs a connection point at your desired location (wiring from the street main cable) and the modem, then basically you just connect your PC to it using either RJ45 or USB port. No authentication (user name, password) is required.

If you have multiple PCs sharing same Internet connection via a router then you connect the latter to the cable modem. In contrast, ADSL connection requires login authentication configured either into the ADSL modem (setting will be lost if reset) or via software installation on your PC provided on a CD from your ISP.

Router users need to manually apply configuration. In terms of speed comparison theoretically, cable modem peak performance can reach networking speed of approximately 30 Mbps using 100 Mbps network Interface card (NIC) whereas ADSL cannot reach 10 Mbps with one exception being VDSL form which is not generally available.

In practice the speed advantage of cable over DSL is much lower than might first be apparent. Both cable modem and DSL performance vary from one minute to the next depending on the pattern of use and traffic congestion on the Internet. This means that both services will rarely if ever reach peak performance. Furthermore, cable modem technology delivers shared bandwidth within the local neighbourhood while DSL delivers dedicated local bandwidth. In summary, both ADSL and cable modem provide reasonably fast and safe Internet access as long as one follows reasonable security precautions.