Google Data Center Technician (DCT) Interview Vocabulary Flashcards

Vocabulary flashcards focusing on networking, hardware, and Linux operating systems concepts for the Google Data Center Technician interview.

Switch

Connects LAN devices and forwards frames using MAC addresses.

Router

Connects different networks and forwards packets using IP addresses.

DNS

Translates domain names into IP addresses; usually uses port 53.

Ping

Tests IP reachability and round-trip response using ICMP.

OSI Model

Seven layers describing how network communication moves from physical media to applications.

Layer 1 (Physical Layer)

Physical layer consisting of cables, optics, connectors, signals, and hardware transmission.

Layer 2 (Data Link Layer)

Data Link layer consisting of Ethernet frames, MAC addresses, switches, and VLANs.

Layer 3 (Network Layer)

Network layer involved in IP addressing and routing between networks.

TCP vs UDP

TCP is reliable and connection-oriented; UDP is faster and connectionless.

DHCP

Automatically assigns IP settings such as address, subnet mask, gateway, and DNS using UDP port 67 for servers and UDP port 68 for clients.

MAC Address

A Layer 2 hardware address used to identify a network interface.

IP Address

A logical Layer 3 address used to identify and route to a host.

Subnet Mask

Identifies which part of an IP address is network versus host.

Default Gateway

Router used to reach destinations outside the local subnet.

ARP

Maps an IPv4 address to a MAC address on the local network.

VLAN

Logical separation of Layer 2 networks on shared switching infrastructure.

Trunk Port

A switch port that carries traffic for multiple VLANs.

Access Port

A switch port assigned to one VLAN for an endpoint.

Link Flapping

A state where a network link repeatedly transitions between up and down states.

SFP

A pluggable transceiver that provides network connectivity over fiber or copper.

POST

Power-On Self-Test checks hardware during system startup.

RAID 1

Mirrors data across drives for redundancy; usable capacity is $50\%$.

DIMM

A memory module installed in a server motherboard slot.

ECC Memory

Memory that detects and corrects certain data errors automatically.

NVMe

High-speed storage protocol designed for SSDs using PCIe.

PSU

Power Supply Unit converts incoming power for server components.

PDU

Power Distribution Unit supplies power to rack-mounted equipment.

NIC

Network Interface Card connects a server to a network.

RAID 0

Striping across drives for performance with no redundancy.

RAID 5

Striping with distributed parity; survives one drive failure.

RAID 10

Mirroring plus striping; combines redundancy with strong performance.

Hot-swappable Hardware

A component that can be replaced without shutting down the system.

FRU

Field Replaceable Unit: hardware designed to be replaced during service.

ESD

Electrostatic discharge that can damage sensitive electronic components.

BIOS / UEFI

Firmware that initializes hardware and starts the boot process.

BMC

Management controller providing remote hardware monitoring and control.

Rack Unit (RU or U)

A rack-height measurement where 1U equals $1.75\,\text{inches}$.

Cable Reseat

Disconnecting and firmly reconnecting a cable to restore a proper connection.

df -h

Linux command showing disk filesystem usage and available space in readable units.

Process vs Service

A process is running code; a service is a background-managed process.

free -h

Linux command showing system memory and swap usage in readable units.

top

Linux command showing real-time CPU, memory, load, and running process information.

journalctl

Linux command displaying logs collected by the systemd journal.

dmesg

Linux command displaying kernel messages, including hardware detection and driver errors.

Root

The Linux superuser account with full administrative privileges.

sudo

Linux command that runs an authorized command with elevated privileges.

PID

Process ID: a unique number identifying a running process.

Linux Kernel

Core OS component managing CPU, memory, devices, processes, and system calls.