On what basis are IP numbers allocated?

Answer

If your question is about ip address allocation by isp:

whenever a user connect to the isp's network, from a specified range, its server allocates a dynamic ip address mostly or it can be static. if it is static, then the user will have the same ip address for a very long time (based on the deal). But if it is dynamic then it means it will change after some time or upon reconnect.

now the if your question is about your LAN (at work etc):

a computer again can have a fixed ip address assigned by the administrator or dhcp server can give your pc an ip address upon start. You may retain the same ip address for some days if such permission has been granted by the admin.

IP addresses in LAN are normally not public addresses and therefore the range may not matter as long as it is in the same network segment.

First answer by Vishwadev. Last edit by Vishwadev. Contributor trust: 35 [recommend contributor]. Question popularity: 13 [recommend question]