Ross Boylan wrote: > On Sun, Sep 6, 2020 at 3:37 PM Dan Ritter <d...@randomstring.org> wrote: > > > The usual way is: > > > > 1. DNS record tied to a static IP address > > 2. IP address handed out by DHCP server based on MAC address of > > the interface > > > > This is especially normal when the root is served by NFS, so PXE > > needs to figure out the right root to hand out -- PXE is > > governed by MAC address, and then you really want the kernel's > > conception of its IP address to remain the same. > > > I don't follow that last part. I thought PXE was irrelevant once the > system was up. And the IP address of the root fs is distinct from the IP > address of the client.
You made me double-check my belief here. I thought that the kernel inherited the IP address from the PXE booter, but I was wrong; there's no mechanism for that. It's an artifact of my own setup, where individual MAC addresses are used to return specific IP addreses. I would still argue that this is a good practice, because it makes debugging easier, but it's not necessary. > > > bit of a hack. Also, I'd like the DNS entry for the system to appear > > only > > > while it is up, and without the client sending a host name that's harder. > > > > That requires a server that listens to a dynamic DNS protocol, > > and a dynamic DNS client on the client system. > > > My server is set for dynamic updates. Since ipconfig sets up the > interface, the usual dhcp client that manages such stuff doesn't come up. > > > Why would you care about the DNS name not being available when > > the machine isn't up? > > > Mostly because the machine might be up, but running a different OS > instance. This applies to non-diskless, non-PXE clients as well. So the > MAC address does not determine a unique system. PXE booting (and grub for > regular systems) provides a menu of possible systems from which to boot, so > I may not know which of them is running until someone makes a selection > from the menu. > > I've been shooting for using the same IP regardless of the OS, but maybe > that's inadvisable. OTOH, for PXE the machine gets an IP before the > selection is made. It depends on the semantics that you're assigning to names and IPs and MACs. IMHO, the physical hardware is important because if there's a problem, I need to know what piece of equipment I will have to walk over to and debug. -dsr-
