The Linux Network Stack
The Linux network stack for someone who knows router CLI but hasn't lived in Linux. Network namespaces, the ip command, interfaces, veth/bridge/tap, and the mental model that maps to what you already know.
Kernel Tuning for RDMA
The Linux kernel knobs that turn a stock host into an RDMA-capable training node. IOMMU, hugepages, kernel cmdline, NIC driver, rdma-core, sysctl.
Debugging Tools You'll Use
The ten Linux commands that 90% of AI-host-side debugging boils down to. ip, ethtool, rdma, ibstat, lspci, numactl, dmesg, ss, perf, and what to look at when each one is wrong.