Google Data Center Technician Interview Study Guide

Comprehensive vocabulary flashcard set covering foundational networking, server hardware, Linux operations, diagnostic tools, and troubleshooting principles from the Google Data Center Technician interview study guide.

Troubleshooting Order of Operations

The recommended sequential workflow for technical troubleshooting: Verify -> Inspect -> Isolate -> Test -> Fix -> Validate -> Document/Escalate.

OSI Layer 1 (Physical Layer)

The first layer of the OSI model, responsible for physical hardware components including cables, fiber, signals, and ports.

OSI Layer 2 (Data Link Layer)

The second OSI layer, responsible for switching, frames, and MAC addresses.

OSI Layer 3 (Network Layer)

The third OSI layer, responsible for network packets, IP addresses, and routing.

OSI Layer 4 (Transport Layer)

The fourth OSI layer, managing end-to-end communication, TCP/UDP protocols, and port numbers.

OSI Layer 5 (Session Layer)

The fifth OSI layer, responsible for starting, managing, and terminating session connections between applications.

OSI Layer 6 (Presentation Layer)

The sixth OSI layer, handling data formatting, encryption, and compression.

OSI Layer 7 (Application Layer)

The top OSI layer, providing user-facing network services such as HTTP, DNS, and SSH.

Ethernet Switch

A Layer 2 networking device that connects devices within the same local network and forwards frames using MAC addresses.

Router

A Layer 3 networking device that connects different networks and forwards packets using IP addresses.

MAC Address

A Layer 2 physical hardware address assigned to a network device and used on the local network.

IP Address

A Layer 3 logical address used to identify and route data to a device across networks.

ARP (Address Resolution Protocol)

A protocol used to find the MAC address associated with a given IPv4 address on a local network.

DNS (Domain Name System)

A network service that translates human-readable hostnames (such as google.com) into numerical IP addresses.

DHCP (Dynamic Host Configuration Protocol)

A service that automatically assigns network configurations to devices, including IP address, subnet mask, default gateway, and DNS server.

TCP (Transmission Control Protocol)

A connection-oriented transport layer protocol that ensures reliable, ordered packet delivery.

UDP (User Datagram Protocol)

A connectionless transport layer protocol with lower overhead and faster speed, but without guaranteed delivery.

Subnet Mask

A configuration that divides an IPv4 address into its network portion and host portion.

Default Gateway

A router address assigned to host devices that directs traffic off the local network to external networks.

ICMP (Internet Control Message Protocol)

A network protocol used for status updates and error messages, heavily relied upon by tools like ping.

traceroute / tracert

A diagnostic tool that lists the network hops a packet takes to reach a destination to help pinpoint network failures or delays.

nslookup / dig

Command-line tools used to query DNS servers and verify hostname-to-IP address resolution.

VLAN (Virtual Local Area Network)

A logical separation of devices into distinct Layer 2 networks regardless of their shared physical switch infrastructure.

Access Port

A network switch port that carries traffic for a single assigned VLAN, typically connected to an endpoint.

Trunk Port

A switch port configured to carry traffic for multiple VLANs simultaneously between network devices.

Standard Port Numbers

Common service network ports: SSH (TCP 22), DNS (TCP/UDP 53), HTTP (TCP 80), HTTPS (TCP 443), DHCP (UDP 67/68), NTP (UDP 123).

Single-mode Fiber

Fiber optic cable designed with a small core diameter for long-distance data transmissions.

Multimode Fiber

Fiber optic cable designed with a larger core diameter, typically used for high-bandwidth, shorter-distance transmissions.

SFP / QSFP

Hot-pluggable network transceivers used to connect switches or servers to optical or copper links; SFP supports a single lane, whereas QSFP supports multiple lanes for higher bandwidth.

Link Flapping

A condition where a physical network link continuously alternates between UP and DOWN states due to hardware, optic, cable, or power issues.

CPU (Central Processing Unit)

The primary processor in a server that executes instructions and processes data for the operating system and applications.

RAM (Random Access Memory)

Fast, volatile system memory used to hold temporary data for active programs and operating system processes.

DIMM (Dual In-line Memory Module)

A physical circuit board containing memory chips that inserts into motherboard RAM slots.

ECC Memory

Error-Correcting Code memory that can detect and correct single-bit memory errors to maintain system stability and prevent data corruption.

NVMe (Non-Volatile Memory Express)

A high-performance storage interface protocol operating over PCIe lanes designed specifically for low-latency solid-state drives.

NIC (Network Interface Card)

A hardware adapter component that allows a server to connect to a local area network.

PCIe (Peripheral Component Interconnect Express)

A high-speed expansion bus standard used for attaching internal hardware components like NICs, GPUs, and NVMe drives.

PSU (Power Supply Unit)

An internal server component that converts AC electricity from a power source into DC voltages required by internal server parts.

PDU (Power Distribution Unit)

A electrical distribution device used to manage and distribute electrical power to server racks and mounted equipment.

RAID 0

A storage array method that stripes data across multiple disks for speed but offers zero data redundancy.

RAID 1

A storage array method that mirrors exact data across two or more disks to provide hardware fault tolerance.

RAID 5

A storage configuration using block-level striping with distributed parity, allowing continued operation following a single drive failure.

RAID 10

A nested RAID configuration combining drive mirroring (RAID 1) and data striping (RAID 0) for high performance and redundancy.

Hot-swappable

A hardware design feature that permits replacing or removing components (such as drives or power supplies) while the system remains energized and functioning.

FRU (Field Replaceable Unit)

A modular system component designed to be removed and replaced on-site by a technician during service operations.

POST (Power-On Self-Test)

Initial diagnostic checks performed by motherboard firmware immediately upon power application prior to booting an operating system.

UEFI (Unified Extensible Firmware Interface)

A modern system firmware standard replacing legacy BIOS, offering support for larger storage drives, fast startup times, and enhanced boot parameters.

BMC (Baseboard Management Controller)

A specialized service processor providing out-of-band monitoring, health telemetry, and remote management of server hardware independently of the OS state.

ESD (Electrostatic Discharge)

The sudden transfer of static electricity between objects, which can permanently damage sensitive server hardware if proper grounding controls are omitted.

Hot Aisle / Cold Aisle

A data center rack layout strategy where cool air is drawn in from the front cold aisle and warm exhaust air is vented into the rear hot aisle for optimized cooling efficiency.

Linux Kernel

The foundational core of the Linux OS that manages hardware resources including memory, process scheduling, storage drivers, and networking.

PID (Process ID)

A unique numerical identifier assigned by the operating system kernel to each active running process.

Daemon / Service

A non-interactive background process in Linux designed to perform continuous system administrative or service roles (e.g., sshd).

sudo

A command utility allowing permitted users to execute system administrative operations with superuser (root) security privileges.

df -h

A Linux utility command used to display active filesystem disk space metrics formatted in human-readable units.

free -h

A Linux utility command used to show physical RAM and swap space utilization formatted in human-readable units.

dmesg

A Linux utility that prints the kernel ring buffer, used to diagnose driver detection, hardware faults, and boot issues.

journalctl

A Linux system command used to inspect and filter log files generated by the systemd journal daemon.

lspci

A command-line tool in Linux used to list details about all PCI and PCIe buses and attached hardware cards.