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I recently installed my first VMware ESXi (4.1) server. Things have gone smoothly in my testing but I have run into one annoying problem:

None of the virtual machines that are running on this ESXi box properly report themselves to the our local DNS server. They appear able to pull an address and DNS info from the DHCP server however but when it comes to reporting their FQDNs to the DNS server, nothing.

Is it something to do with the virtual switch that ESXi runs? Right now the VMs just pull an address on the same subnet as the rest of the servers and I would like to keep it that way if possible. I wonder if the only way to get this to work is to put my VMs on a different subnet and set up routing between them.

What would you guys do?

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2 Answers

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Are these machines joined to an AD domain? If not, then you'll need to configure a connection specific DNS suffix on them for the DNS zone that you want them to register their A records in.

A host that is not joined to an AD domain does not have a primary DNS suffix and as such, you need to configure a connection specific DNS suffix that matches the DNS zone that they should register their A records in.

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These VMs are not joined to the local AD domain. The strange thing is that non-ad IP clients report to DNS just find without being a member of the domain. I did check the primary DNS suffix and like you said it was blank. I added that manually in the adapter config. The awesome thing is now I can see the name resolving, but the wierd thing is that now I am not seeing the entry for it in the DNS console. – Cliff Racer Jul 8 '11 at 15:08
Try running ipconfig /registerdns on one of the clients. Wait 15 minutes and see if the A record is registered. If the DHCP server is joined to the same AD domain as the DNS server and if the DHCP server is configured to always update DNS on behalf of the DHCP client then the DHCP server should update the A record regardless. If the DHCP server is not joined to the same domain as the DNS server or if it's not configured to update DNS on behalf of the DHCP client then you'll need to configure your DNS zone to allow secure and unsecure updates. – joeqwerty Jul 8 '11 at 15:37
a little update: I think the VM I talked about resolved because I actually joined it to the domain. I made anther VM and manually added the primary DNS suffix and it does not appear to be registering in DNS even after doing the CLI command to register. – Cliff Racer Jul 11 '11 at 15:15
That tells me one of two things: 1. The DHCP server is not configured to update A records on behalf of the clients or 2. The DNS zone is not configured to allow secure and unsecure updates. Non-domain joined computers can't register and update their DNS records in a domain DNS zone that's not configured to allow unsecure updates or if the DHCP server is not configured to update A records on behalf of the DHCP clients. – joeqwerty Jul 11 '11 at 19:55
up vote 1 down vote

This is nothing to do with ESXi, it's a VM thing, the vSwitch is just a switch, nothing more, a layer 2 device that knows nothing of IP at all. I have lots of VMs doing exactly what you're doing and they get DHCP addresses and register their DNS names appropriately.

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Thanks! I went back into one of the new VMs on this ESXi box and double checked to ensure the "register connection's address in DNS" is checked and it is. Where else can I check to see where the point of failure is? The logs on the VMs are not giving me anything to go on – Cliff Racer Jul 8 '11 at 14:10
You could do a wireshark trace on the host's trunk/uplink if you really wanted. – Chopper3 Jul 8 '11 at 14:17
downloaded it and trying it now. The strange thing is that it only appears to be the VMs on this system that are not reporting to the DNS server. They will report if they are a domain member but if the VM is not, then they can get a proper IP but no DNS registration. – Cliff Racer Jul 11 '11 at 15:37

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