> For the complete documentation index, see [llms.txt](https://documentation.2pintsoftware.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.2pintsoftware.com/2pxe-server/4.0/configuration/dhcp-configuration.md).

# DHCP Configuration

PXE booting uses DHCP (Dynamic Host Configuration Protocol) to provide clients with network configuration and the information required to start a network boot. When a client PXE boots, it sends a DHCP request that identifies it as PXE-capable and indicates that it is looking for a network boot service.

If the 2PXE Server is on a different subnet from the client, the PXE broadcast will not normally cross the router. You must configure your network so that the PXE request can reach 2PXE. There are two common approaches: DHCP Scope Options and IP Helpers.

## DHCP Scope Options

This approach requires changes to the DHCP server configuration. The DHCP server provides the client with the information it needs to locate 2PXE and download the appropriate boot file.

For an explanation of the required options and configuration instructions, see [Using DHCP Scope Options](/2pxe-server/4.0/configuration/dhcp-configuration/using-dhcp-scope-options.md).

## IP Helpers

If you use IP Helpers to direct PXE traffic, configure your routing hardware to forward DHCP requests from the client subnet to both your DHCP server and the 2PXE Server.

The DHCP server continues to provide the client's IP configuration. The PXE request is also forwarded to 2PXE, where it is processed directly. The request packet contains the information 2PXE needs to identify the hardware type and the machine, allowing it to select and return the appropriate boot information.

IP Helpers are configured on network infrastructure, such as routers or Layer 3 switches. The exact configuration depends on the network equipment. The network team responsible for that infrastructure should configure the appropriate DHCP relay or IP Helper addresses.

When you can configure the network equipment, IP Helpers are generally the preferred approach. They allow 2PXE to inspect the original PXE request and select the appropriate boot response, without relying on DHCP scope policies to determine the boot file for each client architecture.

## DHCP Scope Options vs IP Helpers

Both approaches can direct PXE clients to 2PXE, but they place the configuration in different parts of the network.

| Consideration            | DHCP Scope Options                                                            | IP Helpers                                                           |
| ------------------------ | ----------------------------------------------------------------------------- | -------------------------------------------------------------------- |
| Where it is configured   | DHCP server                                                                   | Routers or Layer 3 switches                                          |
| Network team involvement | May not be required                                                           | Usually required                                                     |
| DHCP configuration       | Requires options and policies to provide the correct boot information         | DHCP continues to provide normal IP configuration                    |
| Boot file selection      | DHCP must return the correct boot file for the client's firmware architecture | 2PXE can inspect the PXE request and select the appropriate response |
| Administration           | DHCP policies may need additional maintenance                                 | Requires network infrastructure configuration                        |

Choose DHCP Scope Options when you cannot make changes to the network infrastructure or when DHCP configuration is easier to manage in your environment. Choose IP Helpers when you can configure the routers or Layer 3 switches and want 2PXE to handle PXE request processing directly.

When using DHCP Scope Options, the iPXE network boot program cannot automatically detect the option values from the 2PXE server. The URL that the client uses to contact 2PXE must therefore be configured through DHCP Option 175. See [Using DHCP Scope Options](/2pxe-server/4.0/configuration/dhcp-configuration/using-dhcp-scope-options.md) for the required URL format and configuration details.


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