17.6.2 NAT DNS changes static reservation host-name

[pzi123]

Normal process of setting up DHCP static reservation is to create DNS A record for the client and then create a host entry in the DHCP configuration to bind IP with the MAC address.

In workstation NAT interface the DHCP configuration file c:/programdata/vmware/vmnetdhcp.conf allows to add host entries with both IP and host-name and the DNS records are created automatically. Unfortunately when the client gets the IP from the DHCP and includes its hostname in the DHCP request, workstation DNS gets updated with that client hostname overriding the DHCP host entry host-name.

For example the host entry for test1 client below with host-name=test1 will be changed in the workstation automatic DNS to the hostname of the client after client connection.

host test1 {
    hardware ethernet 00:0C:29:E5:D5:E4;
    fixed-address 192.168.6.33;
    option host-name "test1";
}

I can see the reasoning for doing that. Unfortunately traditional DNS/DHCP does not behave like that. No environment automatically changes A records after client connection. In fact the opposite is usually done and the client queries it's IP, gets its A record name and sets its own hostname.  Frequently in VMware we deploy a templates with some accidental hostnames and use static reservation to name them. In workstation this is prevented with that automatic A record update. Any ideas on how to stop that update?

[RaSystemlord]

I'm not an expert in networking and that is why I use a different approach.

This is valid to Windows, but in Linux you can do the same. But first, are you sure that if you use Virtual Network Manager to what you desire, it works wrong for you.

What I do, first, I don't fiddle with DHCP or DNS at all. I have:
- use fixed ip's on all computers, outside the range of DHCP
- in "hosts" file, I name all the computers that I want to "see" each other. So, ip and hostname is always found the same way, into both directions of course. I mean all the computers need to name each other there

- reboot is required for this to be in effect (in all applications)

When computers are moved to another host, Virtual Network Editor is needed to change the Host networking (NAT) to be the same as in the original computer. Preferably, you standardise the network ranges among all your computers, first

So, the hostnames are constant. IP's are constant. DHCP can work for other computers where an IP change doesn't matter.

I understand that you talk about DHCP, but generally speaking, kind of related to this: For instance, a hostname change would be bad for applications, which have tens of absolute paths stored in the db for internal purposes (like with SQL Server and some application running on top of it) ... IP change wouldn't matter at all but hostname change would be really bad for SQL Server itself. An IP change would be really bad for Oracle itself (or rather one of its managers), if IP changes AND you do not react before using (one of its) db manager ... or alternatively, you could install Oracle correctly and then the IP change wouldn't matter at all.

So, with applications, this IP/Hostname business is kind of complicated, because different applications have very different issues. Sometimes you can solve it by a couple of mouse clicks in some manger software - sometimes a complete reinstall is more easy. So, that is why I use the approach mentioned above, because that covers all the bases.

[pzi123]

DHCP static reservation is supposed to be equivalent to static IP assignment. The benefit of DHCP static reservation is central management of IP/host-name assignments that is done on the DNS/DHCP server in local configuration files.  This approach is frequently combined with PXE booting and installation of the VMs. I use it to build farms of K8s node VMs or nested ESXi VMs, etc.  Manual IP assignment in client VM hosts files does not work at all in these scenarios.

I guess my mistake is to hope to apply technology used in data centers to the PC hypervisor like Workstation.

[RaSystemlord]

Yes, I was thinking that you had something else in mind for DHCP. Thanks for explaining the scene.

I hope somebody else can help with DHCP server issues in VMware.

[Fred.S]

Is the IP (192.168.6.33) outside of the automatic range?

In the old days (router) I've run into similar issues when fixed IPs where within the DHCP range.