DHCP and DDNS

[paul_collins]

I've setup an ESXi server and got it grabbing it's IP info from DHCP, but I can't seem to get it to send it's hostname information to the DHCP server. I went in and configured the DNS information to be static and set the hostname directly, then told it to restart the management interface but I'm still not seeing it appear in DNS. Is there some kind of hidden switch to get ESXi to send a DDNS update to the DHCP server?

Thanks,

Paul

[weinstein5]

I could be wrong but I do not think ESX supports DDNS -

[paul_collins]

So my only recourse would be to either put a static entry in DHCP and and have it send an update when the ESXi server grabs a lease, or put an extra A record in the DNS?

Can anyone confirm that ESXi really doesn't support DDNS updates?

Thanks,

Paul

[Elitoh · Accepted solution]

It depends on whats running dns and dhcp. Are you using a little router/switch like a linksys or dlink? DNS updates are really week on that type of systme. But if you are using like a windows 2003 server with dns then just add the host record. If its just that you want to put in the computer vs. then Ip then simply give your esxi server a static ip address and add it to you windows host file with teh hostname of the esxi box. DNS on the home grade stuff is crap unless its windows and dhcp.

[paul_collins]

Yea this is on our corporate network. DNS and DHCP is being handled by Win2k3, so it seems that ESXi just isn't sending its hostname info to the DHCP server. I took your suggestion and just made a reservation for it in DHCP and added the A record to DNS directly. Not the solution I really wanted, but ohwell.

Thanks for the help!

Paul

[danielibarnes]

I really wish this was a feature. It's trivial -- just add the option to the DHCP client daemon. Unfortunately for myself, I do not administrate our DNS servers. I analyzed ESXi 3.5 (update 3) and saw that it uses busybox for the DHCP client. In my case, ps -c shows the command line as:

/bin/busybox udhcpc -i vmk0 -p /var/run/dhcp-vmk0.pid --retries=20

It seems like it is started somehow by the esxcfg-dhcp executable, but I've no idea how. The best I could do was to simply kill the old DHCP client and start a new one. I modified the /bootbank/oem.tgz in order for this to occur on bootup. Here is how I did it (after enabling ssh). I don't know if there is any easier way -- I would hope so.

First, I extracted oem.tgz

mkdir /tmp/oem/
tar xzf /bootbank/oem.tgz -C /tmp/oem/
mkdir /tmp/oem/etc/rc.local.d/

The file /tmp/oem/etc/rc.local.d/send-hostname I added is attached to this post because the forum message editor mangled it. Then, I repackaged oem.tgz

chmod +x /tmp/oem/etc/rc.local.d/send-hostname
cd /tmp/oem/
tar czf /bootbank/oem.tgz *

[stillfly]

This fix didn't work for esxi 4.0 - anyone looking to do the same for 4.0 can follow the same instructions and the revised attached send-hostname file

[danielibarnes]

I missed it before, but there is an easy way to set the preferred hostname:

Configuration tab --> Advanced Settings --> misc.PreferredHostName

This will add a parameter to dhclient which sends the value to the DHCP server.

[scottschreckeng]

edit the "/etc/vmware/esx.conf" by updating or adding the line like:

/adv/Misc/PreferredHostName = "your-host-name"