Custom Option 43 Sub-Option Builder

Build an Option 43 hex string from arbitrary sub-option code/type/value rows, for vendors not listed above

Sub-Option 1 Code * Decimal sub-option code, 0-255

Sub-Option 1 Value Type * How to encode the value below

Sub-Option 1 Value * Value for this sub-option

Sub-Option 2 Code Decimal sub-option code, 0-255

Sub-Option 2 Value Type How to encode the value below

Sub-Option 2 Value Leave blank to skip this sub-option

Sub-Option 3 Code Decimal sub-option code, 0-255

Sub-Option 3 Value Type How to encode the value below

Sub-Option 3 Value Leave blank to skip this sub-option

Sub-Option 4 Code Decimal sub-option code, 0-255

Sub-Option 4 Value Type How to encode the value below

Sub-Option 4 Value Leave blank to skip this sub-option

Generated Output

ISC DHCP (dhcpd) Configuration

Add the generated line to your dhcpd.conf file within the appropriate subnet or host block:

Open your /etc/dhcp/dhcpd.conf file
Locate the subnet or host block where you want to apply this option
Add the generated line from above
Restart the DHCP service: systemctl restart isc-dhcp-server

Infoblox Configuration

Use the hex value above to configure DHCP Option 43 in Infoblox:

Log in to the Infoblox Grid Manager (NIOS)
Navigate to DHCP → DHCP Options (or Data Management → DHCP → Options)
Select or create the DHCP option set you want to modify
Click Add or edit Option 43
In the option configuration:
- Set Option Type to "Hex" or "Binary"
- Enter the hex value from above in the Value field
- The format should be: XX:XX:XX:XX (with colons)
Click Save or Save & Close
Apply the option set to your network view, network, or DHCP range as needed

Screenshot placeholder: Infoblox DHCP Options configuration screen

Important: The hex value format uses colons (:) as separators. Copy the value exactly as shown above, including the colons.

Windows DHCP Server Configuration

Configure DHCP Option 43 using the hex value above:

Open DHCP Manager (run dhcpmgmt.msc or search for "DHCP" in Start menu)
Navigate to your DHCP server → IPv4 → Server Options (for all scopes) or Scope Options (for specific scope)
Right-click on Server Options or Scope Options and select Configure Options
In the General tab, scroll down to find Option 43
Check the box next to Option 43
In the Data entry section:
- Select Binary or Hex as the data type
- Enter the hex value from above in space-separated format: XX XX XX XX
- Alternatively, you can enter it as a single hex string without spaces
Click OK to save the configuration

Screenshot placeholder: Windows DHCP Server Options configuration dialog

Alternative Method (PowerShell):

# Convert hex string to byte array and set option
# Replace "HEX_VALUE_HERE" with the raw hex value from above (no spaces, no colons)
$hexValue = "HEX_VALUE_HERE";
$bytes = ($hexValue -split '(..)' | Where-Object { $_ }) | ForEach-Object { [Convert]::ToByte($_, 16) };
Set-DhcpServerv4OptionValue -OptionId 43 -Value $bytes

Note: Replace HEX_VALUE_HERE with the raw hex value from the "Raw Hex" tab above (no spaces, no colons).

Raw Hex Value

This is the raw hexadecimal value without any formatting. Use this for:

Manual configuration in systems that require raw hex
Scripts and automation tools
Testing and validation