PXE (Preboot Execution Environment)
Definition
PXE (Preboot Execution Environment) is an Intel-standard that allows a computer to boot from a network server instead of a local disk. It enables network-based installation of operating systems, diskless workstations, and remote system provisioning.
PXE works at the BIOS/UEFI level, before any operating system is loaded, making it useful for bare-metal provisioning and recovery.
How PXE Works
1. Client BIOS/UEFI → DHCP request (option 66/67)
2. DHCP Server → IP assignment + TFTP server address + boot file name
3. Client → TFTP download boot loader (pxelinux.0, grub.efi)
4. Boot loader → TFTP download kernel + initrd
5. Kernel → Mount root filesystem (NFS/iSCSI/HTTP)
6. OS installer → Install OS to local disk
PXE Components
| Component |
Purpose |
| DHCP Server |
Assigns IP and provides TFTP server info (options 66/67) |
| TFTP Server |
Serves boot files (pxelinux.0, grub, kernel, initrd) |
| Boot Loader |
pxelinux.0, GRUB, iPXE — loads kernel and initrd |
| Kickstart/PRESEED |
Automated OS installation configuration |
| HTTP/FTP Server |
Serves OS installation files (larger than TFTP allows) |
PXE vs iPXE
| Feature |
PXE |
iPXE |
| Protocol support |
Limited (TFTP only) |
HTTP, iSCSI, Fibre Channel |
| File size limit |
~32MB |
Unlimited (via HTTP) |
| Scripting |
No |
Yes (iPXE scripting) |
| UEFI support |
Limited |
Full UEFI support |
| Flexibility |
Low |
High |
| Usage |
Legacy |
Modern replacement |
PXE Use Cases
| Use Case |
Description |
| OS installation |
Network boot into installer (Kickstart, PRESEED) |
| Diskless workstations |
Boot from network, no local disk needed |
| System recovery |
Boot rescue/repair environment |
| Bare-metal provisioning |
Install OS on new servers |
| Live CD/USB |
Boot live OS from network |
| Hardware diagnostics |
Boot diagnostic tools remotely |
PXE in Automation
| Tool |
PXE Integration |
| ** Cobbler** |
PXE management, DHCP, DNS,Kickstart |
| Foreman |
PXE templates, provisioning |
| MAAS |
Ubuntu bare-metal provisioning with PXE |
| IPXE |
Advanced PXE scripting |
| dnsmasq |
Lightweight DHCP + TFTP server for PXE |
- Dhcp — PXE uses TFTP for boot file transfer
- Kickstart — automated installation triggered by PXE
- Ipmi
