Why do ip address changes time to time?

Is there any reason for it? It's general question.

My friend told because of efficiency. But I didn't quite understand .

I am referring to dynamic ip address.

Are you talking about internet IP or your local IP from the router? The principal is the same the DHCP server normally the router gives out IP on lease when the lease expires you would get another IP which may be the same or not as when expires it may be given to another pc that needs an IP. Most router you can set it to give same IP again

samuria said:

Are you.......me IP again

In mobile ISP, they are changing every minute. In broadband connection to desktop, IP not changing.
Looks like you are new to IP address subject because you didn't mention ipv6 etc.

The IP address is not owned by the computer, it is generated by the ISP every time the connection is borrowed, or leased. Dynamic IP address is said to be easier to administer by the ISP.

Isp have to change it as there are limited IP so as soon as you logoff your IP is free so. They can reuse it often home broad band as you are on a lot they often give you the same IP. Not all ISP support ipv6

In mobile, I am getting multiple new ip address , so how to understand that? Are they giving so many ip's so hacker won't trace my mobile?

Dynamic ip easier to administer by ISP ? Means what? What's so difficulty in static IP ??

If your mobile as you connect to a different tower it may well issue a new ip as its a new connection

kingston896 said:

Dynamic ip easier to administer by ISP ? Means what? What's so difficulty in static IP ??

Dynamic IP addresses are much easier to administer. In fact dynamic IP address assignment was developed for that reason.

Look at this as an ISP:
You have several thousand clients. You need to maintain a database of your clients and the IP address assigned. The database must be updated as clients come and go. This takes time and mistakes will be made. The client must manually enter the assigned IP address and DNS IP addresses. You can be sure some will get it wrong, such as entering the wrong numbers or entering them in the wrong place. Your busy support staff will be spending time to resolve these issues.

And there is more.

With dynamic IP address assignment you don't have those problems. Dynamic IP addresses are the default in most computers so the client doesn't need to enter anything. The ISP DHCP server takes care of all the IP address management. Less work for you and your clients and there will be fewer problems. Better for everybody.

Edit Those are the problems with computers at a fixed location. With cell phones and laptop computers connecting to the Internet at multiple locations the problems with static IP addresses are much worse.

LMiller7 said:

The client must manually enter the assigned IP address and DNS IP addresses.

If they enter wrong address, internet won't connect for them. So they call ISP to know their IP. As simple as that. I didn't see any static ip problem here.

Problem with static is limited number of IP addresses to give out. Second, if you move location, you might not necessarily bring statically IP address with you.

kingston896 said:

In mobile, I am getting multiple new ip address , so how to understand that? Are they giving so many ip's so hacker won't trace my mobile?

Are you using WiFi or GPS to connect your mobile to Internet?