DHCP refers to Dynamic Host Configuration Protocol. Basically it’s a mechanism that assigns IP addresses to computers dynamically. DHCP is a role (service) running on a server machine in the network in order to assign dynamic IP addresses to hosts.
DHCP options enables administartors to specify additional DHCP parameters in the form of pre-defined, vendor-specific information that is stored in the options field of a DHCP message. When the DHCP message is sent to clients on the network, it provides vendor-specific configuration and service information.
For some information on BOOTP Vendor Extensions and DHCP Options, see https://techdirectarchive.com/2020/05/18/information-on-bootp-vendor-extensions-and-dhcp-options/
For more information on DHCP, see the following links below
– For more information on Automatic IP Assignment: Dynamic Host Configuration Protocol (DHCP)
– How to install Dynamic Host Configuration Protocol on Windows Server 2019
– On how to configure DHCP: Post-deployment of Dynamic Host Configuration Protocol.
WDS also supports unicast, multicast transmissions, and scheduled casting. By using multicast, we can send one image over the network to the multiple computers. With scheduled casting, we can transfer images at a certain time or after a certain number of computers have contacted the WDS server. This way we can deploy our images off-peak times. We can configure our WDS server to respond to clients in three different ways.
- Not Respond: We can enable this if we don’t want the WDS to respond to client requests.
- Respond to Known: In this method, Active Directory (AD) needs to be available. All devices should be able to contact WDS. This way we can prevent unknown computers from accessing WDS. For devices that are not part of the Domain, they can be pre-staged. By pre-staging our devices, we pre-create the computer account in AD with the relevant names, therefore when the pre-staged computer contacts WDS, it will supply its existing computer name and in this way the WDS server will allow the imaging process.
- Respond to All: Any computer that requests the image from WDS will receive the image.
Configure DHCP Options: To configure the DHCP options, launch the DHCP Manager as shown below. From the Server Manager, there are two ways to launch this
– Simply click on the Tool menu and Select Server Manager or
– Right-click on the DHCP server node, on the server it is installed,
– Click on DHCP Manager.
This will open the DHCP Console as shown below
– Expand the DHCP server
– Expand IPv4 and
– Click on Server Option
– Click on Configure Options
This will open the DHCP Server options as shown below
Note: The Server Option 60 was enabled by default on the screen above, see the scenario one for more details. This is because you have your DHCP server and WDS running on the same host.
Scenario 1: WDS and DHCP on the same server (Clients will find WDS through option 60 in DHCP): For us this is enough since I have my WDS and DHCP on the same server.
– The reason it is selected by default.
Scenario 2: WDS and DHCP in different subnets, you will need to clients will find WDS through option 66 and 67 set in DHCP.
– Options 66 tells the client the name of the WDS server.
– Option 67 tells the client which file to boot from.
Scenario 3: WDS and DHCP server on the same subnet but different servers: Here the clients will find the WDS by broadcast.
To get PXE working on a server that is running both DHCP and WDS you need to enable options 66 and 67. These settings will help your connecting clients to find the appropriate PXE server. The setting is found in the DHCP configuration manager window.
– Expand IPv4 and
– Right-click and select Configure Options.
Scroll down and select the following options below.
066 Boot Server Host Name 067 Bootfile Name
For Option 066 Boot Server Host Name: Enter the string value in the field for “066 Boot Server Host Name”. You can enter the FQDN of your server or the IP Address of the server in the string below.
For Option 067 Bootfile Name: Click on 067 Bootfile Name as shown below.
– Enter the string ” \smsboot\x64\wdsnbp.com” in the field.
– Click on Apply and if you have other settings to enter, click on apply otherwise click on OK.
Where is the BootFile Name located ” \smsboot\x64\wdsnbp.com”? Navigate to the Remote Installation Folder location on the drives. The folder contains the boot images, install images, Windows Deployment Services Management Tool, and PXE Boots. This drive MUST be NTFS formatted. See the image below for the location of the bootfile.
For how to configure Windows Deployment Services on Windows Server 2019″ https://techdirectarchive.com/2020/05/12/configuration-of-windows-deployment-services-wds/
Now all the needed server options to support WDS have been successfully configured. I had to configure options 66 and 67 just to demonstrate how this works. It does not apply to scenario 1. I only need option 60 as I have both my WDS and DHCP server on the same device.
Note: If you have WDS and DHCP on the same server. Clients will find WDS through option 60 in DHCP). For this, we do not need our server to listen to on option 67 and 66. This is why option 60 was selected by default. For this, you can see the WDS settings for DHCP below.
What happens when WDS and DNS is installed on the same server: DNS issues with WDS, to resolve this, see https://techdirectarchive.com/2020/05/26/what-happens-when-wds-and-dns-is-installed-on-the-same-server-dns-issues-with-wds/
I hope you found this blog post helpful. If you have any questions, please let me know in the comment session.