2.1.1. Server Architectures and Distribution Families
💡 First Principle: CPU architecture defines the instruction set the kernel and binaries are compiled for — a binary built for x86_64 is machine code that only an x86_64 processor can execute. Understanding architecture matters when provisioning cloud instances, building containers, and cross-compiling software.
Server Architectures on XK0-006:
| Architecture | Full Name | Common Use Case |
|---|---|---|
| x86_64 / AMD64 | 64-bit x86 | Standard server CPUs (Intel Xeon, AMD EPYC) — most common |
| x86 | 32-bit x86 | Legacy systems; rarely used for new deployments |
| AArch64 (ARM64) | 64-bit ARM | AWS Graviton, Raspberry Pi 4, Apple Silicon, mobile servers |
| RISC-V | Open ISA v5 | Emerging; IoT, embedded, and research systems |
AArch64 is increasingly important in cloud contexts — AWS Graviton instances offer significant cost savings over x86_64 and run standard Linux distributions without modification (assuming software is compiled for ARM64). Docker images must be built for the target architecture; an amd64 image won't run on a Graviton instance without QEMU emulation.
Distribution Families:
The two dominant Linux distribution families differ in package format, package manager, and default tooling choices:
| Characteristic | RPM-Based | Debian-Based (dpkg) |
|---|---|---|
| Package format | .rpm | .deb |
| Low-level tool | rpm | dpkg |
| High-level tool | dnf (modern), yum (legacy) | apt, apt-get |
| Major distros | RHEL, Rocky Linux, AlmaLinux, Fedora, openSUSE/SLES | Ubuntu, Debian, Linux Mint |
| Default MAC | SELinux | AppArmor |
| Default firewall | firewalld | ufw (Ubuntu), iptables (Debian) |
| Service config dir | /etc/sysconfig/ | /etc/default/ |
The exam recommends practicing on both an RPM-based distro (Rocky Linux, AlmaLinux, or Fedora are free) and a Debian-based distro (Ubuntu Server). Commands that differ between families appear frequently in "Given a scenario" questions.
⚠️ Exam Trap: yum and dnf are both used on RHEL-family systems — dnf is the modern replacement and is the default on RHEL 8+/Fedora, but many systems still have yum as an alias. Questions may use either; know that they largely share the same syntax for common operations.
Reflection Question: A script that runs dnf install httpd succeeds on RHEL but the same package name fails with apt install httpd on Ubuntu. A script that runs apt install apache2 works on Ubuntu but dnf install apache2 fails on RHEL. What is happening, and what is the correct package name for Apache on each platform?
