Query

[Simon]

Soporte VT <soporte at vallecastelecom.com> wrote:

> I am writing from a lack of awareness. I work for an ISP provider, which has a DHCP server running perfectly with a public IP address pool.
> 
> Since more of the clients never turn off their routers, it is like the DHCP client holds the IP address information for a long time, or it never changes, in my opinion. I did some test, like rebooting the router or leaving it off for a whole day, and the client takes the same ip address.

That is by design and required by the RFCs. The server tried hard to keep addresses stable - even if a device is left turned off for some time, it will get the same address when turned on unless it’s had to be re-allocated due to churn.

> Is there any configuration in which the IP change insted, like never asign the same IP to the same cliente.

No, as already said, this would be explicitly against the RFCs.

I have to admit, it’s a question that’s not come up for a while, but it used to come up fairly regularly on this list - if you search the archives you should find a few threads about it. There are ways to force address changes, but all of them have downsides - like clients having their connections drop periodically and any open sessions break.
Most threads repeat the above, then add that if your boss is telling you that clients need to keep changing address, then it’s time to look for another job before clients work out why their connections keep dropping periodically, move to a more enlightened provider, and your’s goes bust.

Simon