On Sun, 2022-03-20 at 12:13 -0400, R. G. Newbury wrote: > 'Configuring the DHCP server to work that way', is to set it to > deliver a static address. With a dhcp server, the problem is that any > change in the network, or the items connecting to it, can cause the > dhcp server to deliver a different address to a unit, while a static > address, once set as a static address, will not change. Moreover, a > static address setting is tied to the MAC of the unit, not its FQDN. Again, I'd say generally not (addresses changing willy nilly). Unless you have one of those cutdown DHCP servers which only doles out a tiny number of addresses and has no choice but to share 4 addresses amongst 5 devices. When a device boots up and tries to connect to the network, the DHCP server sees this, and checks if the device has a prior lease. If so, it tries to give it the same one again. The device can say it'd like a particular address, but the DHCP server is boss and *can* honour or ignore that request. When another device boots up and tries to join the network, the same thing happens again. The DHCP server sees if it's previously served that device, and if it has, it'll try to assign it the same address as last time. If it's a new device, it'll try to serve it an address it hasn't given out before to anything else. There are lease time parameters which can configure how short and how long leases last for (e.g. try to keep the lease reserved for a few days if possible, try to avoid changing leases within a few hours), but they tend to be applied to what to do when the server has run out of spare addresses and will have to re-use an address. My experience is that the same devices usually don't get different addresses, and different devices don't usually take over an address used by something else. Part of that equation is the device, as well, it'll usually ask the DHCP server if it can have the same IP as last time, even if the lease period is over. Of course that's no guarantee. Your DHCP server (such as in a router) might have short default times. ISPs often deliberately pick short times, so they can tell customers to disconnect, wait 10 minutes, and try again, when things stopped working (the idea being that they may get a different route, next time, and the ISP won't bother trying to fault find their own network, or it might auto-reset devices when they're free). On my LAN, I've set deliberately very long lease times, just to avoid these nightmares. Leases will be held, if possible, for months. -- uname -rsvp Linux 3.10.0-1160.59.1.el7.x86_64 #1 SMP Wed Feb 23 16:47:03 UTC 2022 x86_64 Boilerplate: All unexpected mail to my mailbox is automatically deleted. I will only get to see the messages that are posted to the mailing list. _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
