Does a Computer Need an Internal Modem With Cable Internet?

By Tom Ianello

An example of a generic cable modem.
i Hemera Technologies/ Images

One of the first types of Internet access was through a dial-up connection, using an internal modem in your computer connected to a phone outlet. Since then, technology has advanced to the point where internal modems have been replaced by Ethernet ports in computers, and the modems themselves are now external devices.

Cable Modem

A cable Internet service must have an external modem installed between the cable access point and your computer. Cable modems generally have a line-in connection for the cable that is carrying the Internet signal, as well as either a USB port for directly connecting to a computer or an Ethernet port that can be used to connect either directly to a computer or to a router. Some modems have both USB and Ethernet ports. Cable modems are always connected to the Internet, meaning you don't have to do anything special to access the Internet, just get on your computer and start browsing.

Ethernet Port

In addition to a cable modem, your computer must have an Ethernet connection in order to connect to the modem. Nearly all current computers have an Ethernet port built in, but there are still some that don't have that functionality. If you have a desktop computer without an Ethernet port, you can install an internal Ethernet adapter, or purchase a USB Ethernet adapter that lets you convert an available USB port into an Ethernet port.

USB Port

Many cable modems also have a USB port built in, allowing you to connect directly to the USB port in your computer. This is useful if you do not have an Ethernet port, or if you have one but it doesn't work. Additionally, you can plug two computers into one modem by using both the USB and Ethernet ports, eliminating the need for a router.


A router allows you to share an Internet connection with multiple computers, either by Ethernet cable or a wireless connection, depending on the type of router you use. Many Internet service providers will supply a modem, but leave it up to the customer to provide their own router. Instead of connecting your computer directly with an Ethernet cable from the modem, you can plug the Ethernet cable into the Internet port on your router, which has multiple Ethernet ports built in for you to connect more than one computer to. A wireless router will make the Internet signal from your modem available as a wireless connection, letting you access the Internet from a computer or other device with a wireless adapter, as long as you're within range of the wireless router.