Chapter 1
HTTP (Hypertext Transfer Protocol)
An Application layer protocol that formulates and interprets requests between Web clients and servers.
RDP (Remote Desktop Protocol)
An Application layer protocol that uses TCP/IP to transmit graphics and text quickly over a remote client-host connection.
POP3 (Post Office Protocol version 3)
An Application layer protocol used to retrieve messages from a mail server.
FTP ( File Transfer Protocol)
An Application layer protocol used to send and receive files via TCP/IP.
SNMP (Simple Network Management Protocol)
An application layer protocol in the TCP/IP suite used to monitor and manage devices on a network.
SMTP (Simple Mail Transfer Protocol)
An application layer protocol responsible for moving messages from one email server to another.
remote application
An application that is installed and executed on a server, and is presented to a user working at a client computer.
static electricity
An electrical charge at rest. When that charge is transferred between two bodies, it creates an electrostatic discharge, or ESD.
hub
An outdated connectivity device that belongs to the Physical layer of the OSI model and retransmits incoming data signals to its multiple ports.
server
Any computer or application that provides a service, such as data or other resources, to other devices.
node
Any computer or other device on a network that can be addressed on the local network.
fire suppression system
Any system designed to combat the outbreak of a fire. These systems might include an emergency alert system, fire extinguishers, emergency power-off switch, and/or a suppression agent such as a foaming chemical or water.
grounding
Connecting a device directly to the earth so that, in the event of a short circuit, the electricity flows into the earth rather than out of control through the device.
trailer
Control information attached to the end of a packet by a Data link layer protocol.
upset failure
Damage that can shorten the life of a component and/or cause intermittent errors
client-server application
Data or a service requested by one computer from another.
payload
Data that is passed between applications or utility programs and the operating system, and includes control information.
topology
How parts of a whole work together
domain
In the context of Windows Server NOSes, a group of users, servers, and other resources that share account and security policies.
MSDS (material safety data sheet)
Instructions provided with dangerous substances that explain how to properly handle these substances and how to safely dispose of them.
trip hazard
Items such as extension cords or tools lying on the ground in a walkway that can cause someone to stumble.
firmware
Programs embedded into hardware devices.
decapsulation
Removing a header or trailer from a lower OSI layer.
SOHO (Small office/home office) network
A network consisting of less than 10 workstations.
header
An area at the beginning of a payload where protocols add control information.
segment
1. A TCP message at the Transport layer. 2. A part of a network.
host
1. Any computer or device on a network that provides or uses a resource such as an application or data. 2. In the context of virtualization software operates and manages guests.
MAC (Media Access Control)
A 48- or 64-bit network interface identifier that includes two parts: the OUI, assigned by IEEE to the manufacturer, and the extension identifier, a unique number assigned to each NIC by the manufacturer.
fragmentation
A Network layer service that subdivides packets into smaller packets when those packets exceed the maximum size for the network.
logical topology
A character of network transmission that reflects the way in which data is transmitted between nodes, including how access to the network is controlled and how specific resources are shared on the network.
knowledge base
A collection of accumulated insights and solutions to the problems encountered on a particular network.
client
A computer or application that makes a request from another computer or application.
star-bus topology
A hybrid topology in which groups of workstations are connected in a star fashion to connectivity devices that are networked via a single bus.
router
A layer 3 device that used logical addressing information to direct data between two or more networks can find the best path for traffic to get from one network to another.
IMAP4 (Internet message access protocol, version 4)
A mail retrieval protocol that allows users to store message on the mail server.
SSL (Secure Sockets Layer)
A method of encrypting TCP/IP transmissions - including web pages and data entered into web forms - en route between the client and server using public key encryption technology.
OSI (open systems interconnection) reference model
A model for understanding, developing, and troubleshooting computer-to-computer communication and was developed in the 1980s by ISO. It divides networking functions among seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
hybrid topology
A physical topology that combines characteristics of more than one simple physical topology.
SFTP (Secure File Transfer Protocol)
A protocol available with the proprietary versions of SSH that securely copies files between hosts.
network service
A resource the network makes available to its users, including applications and the data provided by these applications.
PDU (protocol data unit)
A unit of data at any layer of the OSI model.
TLS (Transport Layer Security)
A version of SSL standardized by the IETF (Internet Engineering Task Force).
AD (Active Directory)
The centralized directory database that contains user account information and security for the entire group of computers on a network.
physical topology
The physical layout of the media, nodes, and devices on a network.
API (application programming interface) call
The process an application uses to make a request of the OS.
encapsulation
The process of adding a header to the data inherited from the layer above.
scalable
The property of a network that allows an administrator to add nodes or increase the size easily.
Data Link layer
The second layer in the OSI model. Its primary function is to divide the data it receives from the Network layer into frames that can then be transmitted by the Physical layer.
Application Layer
The seventh layer of the OSI model. This layer's protocols enable software programs to negotiate formatting, procedural, security, synchronization, and other requirements with the network.
presentation layer
The sixth layer of the OSI model. It is responsible for reformatting, compressing, and/or encrypting data in a way that the application on the receiving end can read.
NOS (network operating system)
The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other network functions.
PPE (personal protective equipment)
Wearable equipment such as goggles that might be required in the workplace to increase safety of workers.
NIC (network interface card)
the device that enables a workstation to connect to the network and communicate with other computers
SSH (Secure Shell)
A connection utility that provides authentication and encryption.
star topology
A physical topology in which every node on the network is connected through a central device.
switch
A connectivity device that logically subdivides a network into smaller, individual collision domains.
UDP (User Datagram Protocol)
A core protocol in the TCP/IP suite that does not guarantee delivery because it does not first make the connection before sending data or check to confirm that data is received.
IP (Internet Protocol)
A core protocol in the TCP/IP suite that operates in the Network layer of the OSI model and provides information about how and where data should be delivered.
TCP (Transmission Control Protocol)
A core protocol of the TCP/IP suite that makes a connection with the end host, checks whether data is received, and resends it if it is not.
catastrophic failure
A failure that destroys a component beyond use.
Remote Desktop Services
A feature on Windows Server 2008 and later editions of Windows Server that allows technicians to manage remote applications.
network
A group of computers and other devices (such as printers) that are connected by and can exchange data via some type of transmission media, such as a cable, a wire, or the atmosphere.
P2P (peer-to-peer) network model
A network in which every computer can communicate directly with every other computer.
ring topology
A network layout in which each node is connected to the nearest nodes so the entire network forms a circle. Data is transmitted in one direction around the circle. Each node accepts and responds to packets addressed to it, then forwards the other packers to the next node in the circle.
LAN (Local Area Network)
A network of computers and other devices that typically is confined to a relatively small space, such as one building or even one office.
MAN (Metropolitan area network)
A network of connected LANs within a limited geographical area, such as multiple city government buildings around a city's center.
CAN (campus area network)
A network of connected LANs within a limited geographical area, such as the buildings on a university campus.
PAN (personal are network)
A network of personal devices, such as a cell phone, laptop, and Bluetooth printer.
WAN (wide area network)
A network that spans a long distance and connects two or more LANs.
client-server network model
A network where resources are managed by the NOS via a centralized directory database.
port
A number that identifies a process, such as an application or service, running on a computer.
protocol
A standard method or format for communication between network devices.
TCP/IP
A suite of networking protocols that includes TCP, IP, UDP, and many others. It provides the foundation for data exchange across the internet.
emergency alert system
A system that typically generates loud noise and flashing lights in response to a fire. The system might also be able to send alert messages to key personnel or make networkwide announcements.
Telnet
A terminal emulation protocol used to log on to remote hosts using the TCP/IP protocol.
bus topology
A topology in which a single cable connects all nodes on a network without intervening connectivity devices.
connection-oriented protocol
A type of Transport layer protocol that requires the establishment of a connection between communicating nodes before it will transmit data
connectionless protocol
A type of Transport layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data.
mesh topology
A type of network in which several nodes are directly interconnected and no single node controls communications on the network.
IP Address
A unique Network layer address assigned to each node on a TCP/IP network.
fail open
System default that allows access during a system or network failure.
fail close
System default that denies access during a system or network failure.
AD DS (active directory domain services)
The Active Directory service that manages the process allowing a user to sign on to a network from any computer on the network and get access to the resources that Active Directory manages.
backbone
The central conduit of a network that connects network segments and significant shared devices (such as routers, switches, and servers) and is sometimes referred to as "a network of networks."
frame
The entire Data Link layer message, including the header, payload, and trailer.
packet
The entire Network layer message, which includes the segment (TCP) or datagram (UDP) from the Transport layer, plus the Network layer header.
session layer
The fifth layer in the OSI model. This layer describes how data between applications is synced and recovered if messages don't arrive intact at the receiving application.
Transport layer
The fourth layer of the OSI model. It is responsible for transporting application layer payloads from one application to another.
physical layer
The lowest, or first, layer of the OSI model. This layer is responsible only for sending bits via a wired or wireless transmission.
OSHA (occupational safety and health administration)
The main federal agency charged with regulating safety and health in the workplace.
network layer
The third layer in the OSI model. This layer is responsible for moving messages between networks. (sometimes called the internet layer)
ESD (electrostatic discharge)
The transfer of electrical charge between two bodies, such as when a technician touches a computer component.
