Home > DNS, vCenter Server, VMware > HOWTO: Fixing mixed FQDN/Host naming in vCenter

HOWTO: Fixing mixed FQDN/Host naming in vCenter

Have you ever run across an environment, where no matter what you do, you can’t seem to get the ESXi host to register as a FQDN? Have you ever had to work in an environment without AD and without local DNS? Yeah – it’s tons of fun. The customer is always right though, and while they have some Windows systems, this is what they grew the company being used to, and use IP’s for everything. Such is life. Let’s talk about how to fix the hosts though, without trying to force AD and full on DNS naming down their throats.

First, the problem:

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That name WAS specified with a FQDN. Then it went away.

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And this is what it looks like in vCenter. I realize that this is going to be tough to demonstrate properly while redacting some of the names, but we’ll get the general point across. Here you can see that the first two hosts are added with their FQDN, but the 3rd is just using the hostname. I removed and re-added the host, reset settings at the DCUI, nothing made a difference.

When you try updating the configuration from the DCUI, you’ll get:

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So it DOES show up.

When you try to add it (or add it back) to vCenter you see:

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Clearly, I’m specifying the FQDN. Click Next though….

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Someone want to tell me where my FQDN went?

The answer, seems to be in due to it having previously been added incorrectly. I found a VMware KB that talks about how to reconfigure it – WITHOUT removing it from Inventory first – which I still haven’t gotten working before finding the KB. Remember, removing the host from inventory removes all history and performance data for it – something you MAY not want to do!

So I follow all these steps:

· Disconnect (not Remove, if you want to keep performance stats) the host in vCenter

· Connect the vSphere Client to the host directly and remove the “vpxuser” user

· Reconnect the host, which should find the new host name.

And no go. Same as above.

Remember now, this site doesn’t have AD or DNS. So I started looking around. Here’s what existed prior, most of which I knew, but working in an environment like this isn’t ‘normal’ for me, so I didn’t think a lot about it:

· The OLD vCenter v4.0 was running DNS in a half-ass way on 192.168.100.20

· The NEW vCenter v5.5 server I had made a C:\WINDOWS\SYSTEM32\DRIVERS\ETC\HOSTS file with entries for the hosts

· Hostnames were first then FQDN. This means the first name it found to resolve would be the hostname alone

· DNS on this NEW vCenter v5.5 server was pointing at the old server – something I did so I could get started, but didn’t finish up. It never knew about this 3rd host.\

So – what fixed it? Some combination of:

· Add DNS role to the new vCenter server. Not a great place for it, but then at least I HAVE DNS available

· Add the Hosts (and iDRAC records, and whatever else) to the new zone you create in DNS

· Modify the local HOSTS file to be FQDN then Hosts – or remove it altogether is probably a better option

· From an administrative CMD prompt on the vCenter server, run “ipconfig /flushdns”.  You have to do this on the vCenter Server, not where you are running the vSphere Client from (which MAY be the server, I don’t know what you’re doing), because the client is telling the server to add the host – and thus, vCenter is doing the resolution, not your client system. 

· Re-add the host:

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Yeah. That’s right. It’s finally there J

Another quick issue to note with lack of DNS – Veeam was giving NFC issues trying to back up VM’s on this 3rd host. Similar issue. IT was pointing at the old DNS, which only knew about hosts 1 and 2. While vCenter was able to find the hosts, Veeam couldn’t resolve them directly, and got angry.

Moral of the story – healthy DNS and name resolution makes for less drinking.

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Categories: DNS, vCenter Server, VMware
  1. September 30, 2014 at 7:54 AM

    nicely written.

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