You can use the IP address a user is coming in on to assign them a credential. This is handy if you know the IP addresses your users will be coming in on. For instance, at a university all the students using the school network to connect will only have a specific IP address or IP range they could connect with. You can then assign those users the credential you would like all the students to have. Then if someone tries to connect from outside the network they would be assigned a lesser credential or even the most restricted credential depending on how you want to design it.
If you want to assign a range of IPs start with the lower number and end with the higher number address. If you want to specify a single IP address put it in both Start IP and End IP.