Posts Tagged ‘DHCP’

(Microsoft) Vendor specific DHCP options explained and demystified

Written by Ingmar Verheij on July 12th, 2013. Posted in Demystified, Other

DHCP servers can send vendor specific options to clients to granularly control configuration. Microsoft clients are out-of-the-box prepared to receive Microsoft Windows specific options while Microsoft DHCP servers have the ability to send DHCP options only received by Windows clients.

Some applications use the content of a DHCP option to receive configuration data, for example Microsoft Lync or RES Workspace Manager. Since this applications only run on Microsoft Windows its no more than logical to only send this option to Windows clients.

In this article I’ll explain how this mechanism works and how you can send Microsoft Windows specific DHCP options from a non-Microsoft DHCP server (like a Linux or Lucent-Alcatel VitalQIP appliance).

Read DHCP options received by the client

Written by Ingmar Verheij on July 12th, 2013. Posted in PowerShell

ipconfig /all

When a DHCP client receives information from a DHCP server only basic information, like IP / subnet / gateway / dns /etc, is visible. In some situations clients also receive DHCP options to set specific settings or application configurations (for example with Microsoft Lync or RES Workspace Manager). Knowing what options are received by the clients helps you troubleshoot.

There are multiple road that lead to Rome, in this article I’ll show you three. For one of them I created a PowerShell script which you can run on any machine.

How to disable the DHCP server on an Apple Airport

Written by Ingmar Verheij on January 2nd, 2013. Posted in No category

The Apple Airport (extreme) is “in my humble opinion” a very good access point for home and small office use. As with other Apple products it’s really a dummy-proof products that’s easy to setup and use. But for the more adventurous user the it might feel as if you’re force to do what Apple tells you to do (sounds familiar?).

For instance disabling the DHCP server is not an option if you’re sharing a public IP (better known as network address translation – NAT). If you want to run your own DHCP server (where you can configure stuff like DHCP options) you have two options.

Configure hostname via DHCP

Written by Ingmar Verheij on July 25th, 2012. Posted in Other

Windows 8 - HostnameA system can be identified on a network with a MAC address, IP address or its hostname. The hostname is the most readable form for humans, especially because you have the ability to change the hostname (unlike a MAC address and only partially for an IP address).

Giving the device a human readable hostname makes it easier to troubleshoot issues and is sometimes required to to apply to a naming convention. Having an asset tag on the device makes it easier for a user to explain what device he/she is using.

But what if you’re unable to change the hostname of a device or don’t want to specify this for each device? Think of thin clients (or zero clients) like a HP Smart Zero Client where you can’t (or want) to configure the hostname per device.

Well, you can push the hostname via the Dynamic Host Configuration Protocol (DHCP).

WinPE: Restarting DHCP client service

Written by Ingmar Verheij on July 7th, 2011. Posted in Deployment

A bare-metal deployment is build using Altiris Deployment Solutions (HP Rapid Deployment Pack, to be precise). When a client boots Windows PE 2.1 to execute a job (installation of operating system) it doesn’t seem to get an IP address from the DHCP server (Restarting DHCP client service: retry x).

WinPE : Restarting DHCP client service: retry

 

 

 

 

 

 

 

 

 

This is strange since the WinPE 2.1 image is downloaded via a PXE boot which acquired a IP address from the DHCP server without problems, the DHCP mechanism is working.

This caused me some serious headache a few months ago (at another customer). I investigated the problem and found the cause of the problem.

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