Removing DHCP options 66 and 67 for WDS PXE booting

When our Specops Deploy customers run into errors during PXE boot, the likely culprit is often DHCP scope options 66 and 67. Aside from Microsoft not supporting the use of the aforementioned options to redirect PXE clients, it can be limiting as it will not work when there are UEFI and BIOS based machines on the same network. When DHCP options 66 and 67 are configured, all PXE clients download and boot the same Network Boot Program, thus hindering support for different architectures.

The Specops recommendation is to delete the DHCP scope options 66 and 67, configure IP Helpers on the switches. Here is a small script that can take care of removing the scopes:

@Echo off

netsh dhcp server \dhcp.server.domain.com dump | findstr /i /c:"com Add Scope" > c:tempAllscopes.txt  

setlocal ENABLEDELAYEDEXPANSION  

for /F "Tokens=1-10" %a in (c:tempAllscopes.txt) do (   

REM NOTE: IT's just showing what would be done. No actual change is done right now!! 

REM NOTE: Remove ECHO from these two lines to make the script active.  

echo netsh DHCP Server \dhcp.server.domain.com Scope %f Delete OptionValue 66

echo netsh DHCP Server \dhcp.server.domain.com Scope %f Delete OptionValue 67 

) 

del c:tempAllscopes.txt

# End of Script

Of course, you will need to replace dhcp.server.domain.com with the FQDN of your DHCP Server.

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Written by

Johan Soderstrom

Product Specialist, Specops Software

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