If you can use something, it's useful. Useful things are handy for whatever you're doing. If something is just what you need or you just find it helpful, then it's useful. A hammer is useful in building many things. Coasters are useful if you don't want a coffee table to get stains. College degrees are useful â or necessary â for many careers.
Where is the security key on a comcast modem located? The security key on a Comcast Modem is located next to the serial  number of the unit. Sometimes the serial number is the number used  as a security code if it is not printeâ¦d on the device. (MORE) 1 person found this useful.
Connect an Ethernet cable from the Comcast modem to the Ethernet port on your computer. If the modem connects to a router, unplug the Ethernet connector from the router and plug it in to your computer's Ethernet port. If the Comcast device combines a modem and router, it may have a single Ethernet port or multiple numbered ports. Connect to any of these ports. Open your browser and type 192.168.100.1 into the address bar. If this address fails to resolve, check your Comcast manual for the modem's IP address. Alternatively, press Win-R, type cmd (without quotes) and press Enter to open a Command Prompt window.