Pxe¶
10 cards — 🟢 3 easy | 🟡 4 medium | 🔴 3 hard
🟢 Easy (3)¶
1. What two DHCP options are critical for PXE boot, and what does each specify?
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Option 66 (next-server) specifies the TFTP server IP, and option 67 (bootfile name) specifies the path to the bootloader file (e.g., pxelinux.0 or ipxe.efi).2. What is the goal of zero-touch provisioning?
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Rack a server, plug in power and network, and it bootstraps itself to a production-ready state without any manual intervention.3. How does the DHCP server differentiate between UEFI and Legacy BIOS PXE clients?
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It checks the architecture option (option arch). If the value is 00:07, the client is UEFI and receives an EFI bootloader (e.g., ipxe/snponly.efi). Otherwise it receives a legacy bootloader (e.g., pxelinux.0).🟡 Medium (4)¶
1. Why do modern PXE setups chainload from PXE to iPXE, and what protocol does iPXE use instead of TFTP?
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iPXE supports HTTP-based boot, which is significantly faster than TFTP. Chainloading lets the initial PXE ROM hand off to iPXE so that the kernel and initrd can be downloaded over HTTP.2. What does the %post section of a Kickstart file do, and why is it important for provisioning?
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The %post section runs shell commands after the OS is installed — typically registering with config management, deploying SSH keys, and phoning home to the provisioning server to signal completion. It bridges the gap between bare OS install and production readiness.3. What ipmitool command forces a server to PXE boot on its next power cycle?
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ipmitool -I lanplus -H4. How does the Redfish API set a one-time PXE boot on a server?
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By sending a PATCH request to /redfish/v1/Systems/1 with the body {"Boot": {"BootSourceOverrideTarget": "Pxe", "BootSourceOverrideEnabled": "Once"}}. Redfish is the modern REST-based successor to IPMI.🔴 Hard (3)¶
1. What is ONIE and how does it differ from standard PXE?
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ONIE (Open Network Install Environment) is the PXE equivalent for network switches (Cumulus Linux, SONiC). Unlike server PXE which boots an OS installer via TFTP/HTTP, ONIE discovers a network OS installer via DHCP options, HTTP discovery, USB, or TFTP fallback, then installs the NOS and reboots.2. What are the key components of a provisioning network architecture, and why is the provisioning network isolated?
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Key components: DHCP+TFTP server (e.g., dnsmasq), HTTP server (nginx) for OS images and kickstart files, config management (Ansible) for post-install, and a CMDB for inventory tracking. The provisioning network is isolated on a separate VLAN to prevent PXE traffic from interfering with production and to secure the out-of-band management plane.3. What types of checks should a post-install validation script perform before marking a server as production-ready?