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.
Some wireless router manufacturers set a default security key or password, which may be on the bottom of your router or in the routerâs documentation. Look for the following terms: 1  Security Key. 2  Wireless Key. 3  WPA Key. 4  WPA2 Key. 5  WEP Key.tep 3: Enter the user name and password to open your routerâs configuration webpage. Most router documentation includes the default user name and password. Step 4: On the configuration webpage, look for a wireless or wireless settings option. Step 5: Now, look for a security or wireless encryption setting.