Question: How do I lock the ip address so all the employees have to login from their work computers?
From your administrator dashboard go to Settings -> IP Address Locks and create an IP lock. Buddy Punch will show the current IP address of the machine you're using. After you save that IP Address, you can assign employees to that IP Address. Typically an IP Address will be shared by all machines in your work location.
Once that lock is setup, your employees will only be allowed to log in from that specific IP Address.
Question: What's an IP Address?
The IP Address you are locking to comes from your ISP. This is not an internal IP Address. Locks are best used in office environments so you can lock your employees to that office. Cell phones, if using a cellular connection, will have randomly assigned IP Addresses that will change. You can use an IP Lock with cell phones but they would be required to use Wi-Fi in order to use the IP address that you are locked to.