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Change DNS server on vLCM Appliance

Changing the DNS server configuration on your servers is not a task you do on a daily basis. But when you have to, it is not always a straight forward action, as I experienced when trying to change the DNS server on the VMware Life Cycle Manager Appliance.

Changing the DNS configuration under Windows is no big deal and is as easy as next, next, finish. Under linux however there are multiple ways to accomplish this task depending on the linux distribution. In most cases the easiest and common way is to edit /etc/resolv.conf and restart the service.

In this case, I am working with a virtual appliance, so I want to keep the editing on the command line to a minimum.  Virtual appliances are normally managed through a management webpage, and for the vLCM appliance this is equally so. I login to the vLCM management page and under settings I see the configured IP and DNS configuration.

Unfortunately, I can only view the configuration but can’t make any changes. So I searched the VMware knowledgebase to see what the supported method for changing DNS on Photon OS was, but got nothing. Even a Google search didn’t give any good results. This left me with no other option than to dive into the command line and edit the configuration by hand.

As mentioned earlier, most linux based distributions use resolv.conf as the configuration file for DNS. However upon opening resolv.conf I saw that Photon uses “systemd-resolved” to manage name resolving and that I shouldn’t edit this file by hand.

When working with system and DNS there a few places where you can configure settings. Let’s look at them for a second:

  • /etc/resolv.conf is a symbolic link to /run/systemd/resolve/resolv.conf and is the running configuration which must not be edited by hand.
  • /etc/systemd/network/10-eth0.network is the configuration file for the vm’s ethernet adapter. You set the IP address, subnet mask and gateway here, but can also specify search domains, NTP and DNS.
  • /usr/lib/systemd/network this folder contains the configurations of other (virtual) adapters on the system
  • /etc/systemd/resolved.conf this file contains the configuration of DNS that would normally be located in resolv.conf

I changed both 10-eth0.network and resolved.conf with the desired DNS servers and search domains, restarted the services, and for a short time everything seemed to work. But after a reboot all settings where back to the old configuration. I was rattled and searched for some other configuration files, looked through a lot of log files, but couldn’t find the culprit.

When all seemed lost, I had a bright moment. I did a search for the old DNS IP in all files (grep -rnw '/' -e '172.25.168.3'), and there between all the rows of text I saw the mentioning of “/opt/vmware/etc/vami/ovfEnv.xml”.

ovfEnv.xml is a file that is created at the deployment of an OVF and apparently is loaded every time the VM boots. I changed the configuration in the XML file and after a reboot the new configuration was still there.

Please wait for the Local Session Manager

Author : Ingmar Verheij
I’ve built a lab to run some tests on Citrix XenApp. Since this is a lab environment I do not have enough resources to create dedicated machines for each role. Therefore I found it justified to create a virtualized domain controller (dc001.domain.local) with multiple roles and multi-homed (Boooohhh, I know). The machine is not only a domain controller but also has the DNS and DHCP role.

The following network interfaces are present on dc001.domain.local:

  • Local Area Connection 1 : 192.168.1.1/24
  • Local Area Connection 2:  192.168.2.1/24

The Citrix XenApp server is a dedicated physical machine with a single network interface:

  • Local Area Connection 1 : 192.168.1.2/24

After creating a published desktop I’ve tried to connect from a machine in the 192.168.1.0/24 subnet. The session keeps waiting with the message ‘Please wait for the Local Session Manager’.

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Replacing a network card of a DC (Virtual Machine)

When you want to replace the old virtual network card for a VMXNET3 network card of a Domain controller (DC) and when the DC is also DNS server (AD integrated) and the only one in the domain you may encounter some problems.  Yesterday i replace the old network card for a VMXNET3 adapter in a DC that was the only DC in the Domain (yes i hear you 1 DC = no DC ) and i encounter the following errors on the server:

 DC error 4007 DC error 4015 DC error 6702

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vCenter on Windows 2008 (R2) and 32 bit ODBC DNS

When installing vCenter on Windows 2008 R2 and you’re planning to connect to a Windows 2008 SQL server you must use a 32 bit ODBC DNS. This is old news for the most of us. But When your planning to use the Windows 2008 (R2) as the platform for vCenter you must first install the Microsoft SQL Server 2008 Native Client on the server or else there is no Native client visibly in het selection menu form ODBC.This dynamic-link library is not default present on your system en must be installed separately.

So download the Microsoft SQL Server 2008 Native Client for W2008 or W2008R2. Watch out read the page carefully because there are a lot of download links on them. You must have the Microsoft SQL Server 2008 Native Client. install this on the system you plan to use for vCenter. Go to %systemdrive%SysWOW64odbcad32.exe and make you’re 32 bit DNS in the System DNS tab. For more information see ICT Freak