Resolving Synology NAS unable to display Child Domain issue

You will encounter you Synology NAS unable to display the Domain or Child Domain after you update it's firmware.

Below is how to resolve this kind of issue based on my experience.

Login with Root account into your Synology by using one of terminal program.

Key in  "net ads info -S " Command  and enter to check the server time sync.

If you see "Failed to get server's current time!" error as below picture, keyin "synowin -updateDomain" command and enter.




After that re-join domain your Synology by using GUI mode and follow the below steps.
If you want to re-join domain first and try, just need to proceed below steps too.

Key in "net ads auth -P -S " command and enter to test your system account that you used when joining domain.

If you do not see "Logon Server error, key in  "net ads auth -P -S " command and enter.



Check DNS setting of your DC by keying in "net lookup dc " command and check Time Sync setting by keying in "net ads info -S " command and enter.




If you do not see any error after key in both commands, just login to Synology NAS with GUI and open Directory Services from Control Panel. You will see your Domains again.

Please key in your full domain name in   of each command which disappeared in your Synology NAS.

Take note all Commands are case sensitive.

I've tested on My Synology NAS Model RS2212RP+ with Firmware Version DSM 5.1-5022 Update 2.

Have a good time.
(Be knowledgeable, pass it on then)

Why do we need network virtualization?

We need to think about Server Virtualization first if we want to talk about Network Virtualization.

In the era of cloud computing, servers are virtualized and used in Data Centers.

We are facing a lot of problem when we virtualized our Servers,

1) Routing and Switching Problem

Routing become the issue when we create Virtual Switch and VLANs according to production requirement.
Network Team might need some time to change on their end to meet with Server Virtualization Team changes on their end.



၂) Firewall Services

Physical Firewall are difficult to manage due to the large number of rules needed to satisfy business requirements.
New applications, new projects, and new networks all come with potential security requirements, which impact centralized firewall management.



၃) Load Balancing

Let's say your company deploys a new physical load balancer for each tenant, resulting in increased capital expenditures.
Once a tenant reaches their maximum capacity, it can be difficult to scale.

၄) VPN Services

Your company supports a single hardware VPN solution for multiple teanants currently and once a tenant reaches their maximum capacity, it is difficutl to scale.




These facts are just fews things that we will face when we use server virtualization without network virtualization.
Server Virtualization Team need to wait Network Team to make changes to meet with updates.
Can you imagine how difficult if it is at Data Center Network without Network Virutalization?

That's why we need network virtualization solutions.

Anyway, this post is just overview for network virtualization and yes I might missed a lot of things.

Reference: VMware Network Virtualization Fundamentals.

Have a good time.
(Be knowledgeable, pass it on then)

Resolving Cisco VPN Client 412 Error

You can get below VPN Client Error at user side sometime.

Reason 412:The remote peer is no longer responding.


You would see a lot of resolving method on Internet for user side.

But the above error is not from User side. It is come out from your Network (Firewall, IPS, Server) actually.

The error mentioned that client couldn't get DHCP, Default Gateway and DNS setting from your Network when they are requesting.

For example, Dynamic Host Configuration Protocol Filter has been blocked from IPS in my network actually.

After I permit this filter, all my VPN Client able to connect VPN Connection successfully.

So, you should look at your IPS or Firewall that could filter DHCP Request if you also facing this kind of issue.

Have a good time.
(Be knowledgeable, pass it on then)

Fixing IP address already assigned to another adapter error in VMware

Sometime, you could see below error when you need to modify or add IP address on existing network adapter of your VM.


According to VMware support this error can occur also if
- You have upgraded VMware virtual network adapters (for example, when you migrate a virtual machine from an older to a new version of VMware software).
- You have added and removed network adapters multiple times.
- You may see this if you recently performed a P2V and the resulting virtual machine still has the physical NICs and drivers for those NICs present. These ghost NICs have the old IP address and the virtual NIC cannot be assigned the same IP address.

This issue occurs if a network adapter with the same IP address is in the Windows registry but is hidden in the Device Manager (My Computer > Properties > Hardware > Device Manager). This hidden adapter is called a ghosted network adapter.
Using the Show hidden devices option in the Device Manager (View > Show hidden devices) does not always show the ghosted adapter to which that IP Address is assigned.
So how do we fix it? First make the ghosted network adapter visible in the Device Manager and uninstall the ghosted network adapter from the registry:

Click Start > Run.
Type cmd and press Enter.
At the command prompt, run this command:
set devmgr_show_nonpresent_devices=1



Note: If this command does not work (a possibility in Windows Server 2000 and 2003), you may need to add the parameter to Windows and set its value:

a. Right-click the My Computer desktop icon and choose Properties.
b. Click the Advanced tab and select Environment Variables.
c.  In the System variables section, click New.
d.  Set the Variable name to devmgr_show_nonpresent_devices and set the Variable value to 1 to enable the parameter.
e.  Click OK to add the variable to Windows.
4. Start the Device Manager by running this command from the same command prompt:
start devmgmt.msc
5. Click View > Show Hidden Devices.
6. Expand the Network Adapters tree (click the plus sign next to the Network adapters entry).
7. Right-click the dimmed network adapter, then click Uninstall.
8. Once all of the grayed out NICs are uninstalled, assign the IP address to the virtual NIC.




Well. I hope you have some fun with this post when you face with such kind of error with your VM.

Have a good time.
(Be knowledgeable, pass it on then)