Term | Definition |
Active Directory (AD) | the centralized directory database that contains user account information and security for the entire group of computers on a network. |
Active Directory Domain Services (AD DS) | The Active Directory service that manages the process that allows a user to sign on to a network from any computer on the network and get access to the resources that Active Directory allows. |
API (application programming interface) call | The process an application uses to make a request of the OS. |
Application layer | the seventh layer of the OSI model. Application layer protocols enable software programs to negotiate formatting, procedural, security, synchronization, and other requirements with the network. |
ARP (Address Resolution Protocol) | A core protocol in the TCP/IP suit that belongs in the Network layer of the OSI model. ARP obtains the MAC (physical) address of a host, or node, and then creates a local database that maps the MAC address to the host’s IP (logical) address. |
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.” |
Bandwidth | (1) The amount of traffic, or data transmission activity, on a network. (2) A measure of the difference between the highest and lowest frequencies that a medium can transmit. |
Best-effort protocol | A type of Transport layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data. |
Bus topology | A topology in which a single cable connects all nodes on a network without intervening connectivity devices. |
Call tracking system | A software program used to document technical problems and their resolutions; also known as help desk software. |
CAN (campus area network) | A network of connected LANs within a limited geographical area, such as the buildings on a university campus. |
Catastrophic failure | A failure that destroys a component beyond use. |
Client-server applications | Data or a service requested by one computer from another. |
Client-server network model | A network where resources are managed by the NOS via a centralized directory database. |
Connectionless protocol | A type of Transport layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data. |
Convergence | The use of data networks to carry voice, video, and other communications services in addition to data. |
Data Link layer | The second layer in OSI model. also called the Link layer, bridges the networking media with nw layer. Its primary function is to divide data the data it receives from the Network layer into frames that can be transmitted by the Physical layer. |
Data Link layer address | The process by which devices determine which device may access the network at any given time. |
Datagram | A UDP message. |
Decapsulation | Removing a header or trailer from a lower OSI layer. |
Delay-sensitive | Transmissions that will suffer significantly compromised user experiences if portions of the transmission are delayed, such as with voice and video transmissions. |
Demarc | The point of division between a telecommunications service carrier’s network and a building’s internal network. |
Demarcation point | The point of division between a telecommunications service carrier’s network and a building’s internal network. |
Domain | In the context of Windows Server NOSs, a group of users, servers, and other resources that share account and security policies through a Windows Server NOS. |
Electrostatic discharge (ESD) | The transfer of electrical charge between two bodies, such as when a technician touches a computer component. |
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. |
Encapsulation | The process of adding a header to the data inherited from the layer above. |
Fail close | System default that denies access during a system or network failure. |
Fail open | System default that allows access during a system network failure. |
File server | A specialized server that enables clients to share applications and data across the network. |
File services | The functions of a file server that allow users to share data files, applications, and storage areas. |
Fire suppression system | Any system designed to combat the outbreak of a fire. A fire suppression system might include an emergency alert system, fire extinguishers, emergency power-off switch, and/or a suppression agent such as a foaming chemical or water. |
Fragmentation | A network layer service that subdivides packets into smaller packets when those packets exceed that maximum size for a network. |
Frame | The entire Data Link layer message, including the header, payload, and trailer. |
FTP (File Transfer Protocol) | An application layer protocol used to send and receive files via TCP/IP. FTP uses port 20 for data and port 21 for file transfer control information. |
Global account | A user’s domain-level account, also called a global username or network ID, which is assigned by the network administrator and is kept in Active Directory. |
Grounding | Connecting a device directly to the earth so that, in the event of a short, the electricity flows into the earth rather than out of control through the device. |
Hardware address | The process by which devices determine which device may access the network at any given time. |
Header | An area at the beginning of a payload where protocols add their own control information. |
Heating, ventilation, and air conditioning (HVAC) system | A system that controls the environment in a data center, including the temperature, humidity, airflow, and air filtering. |
Host | (1) Any computer or device on a network that provides a resource such as an application or data. (2) In the context of virtualization, the physical computer on which virtualization software operates and manages guests. |
HTTP (Hypertext Transfer Protocol) | An application layer protocol that formulates and interprets requests between Web clients and servers. HTTP uses TCP port number 80. |
HTTPS (HTTP Secure) | The URL prefix that indicates that a Web page requires its data to be exchanged between client and server using SSL, or TLS encryption. HTTPS uses TCP port number 443. |
Hybrid topology | A physical topology that combines characteristics of more than one simple physical topology. |
ICMP (Internet Control Message Protocol) | A core protocol in the TCP/IP suit that notifies the sender that something has gone wrong in the transmission process and that packets were not delivered. |
IMAP4 (Internet Message Access Protocol, version 4) | The most commonly used form of the Internet Message Access Protocol (IMAP). |
IP (Internet Protocol) | A core protocol in the TCP/IP suit that operates in the Network layer of the OSI model and provides information about how and where data should be delivered. IP is the subprotocol that enables TCP/IP to internetwork. |
IP address | A unique Network layer address assigned to each node on a TCP/IP network. IPv4 addresses consist of 32 bits divided into four octets, or bytes. IPv6 addresses are composed of eight 16-bit fields, for a total of 128 bits. |
Knowledge base | A collection of accumulated insights and solutions to the problems encountered on a particular network. |
Layer 2 switch | The least intelligent type of switch because it is nonprogrammable. Layer 2 switches are incapable of transmitting messages outside of the LAN. |
Link layer | The second layer in OSI modelr, also called the Link layer, bridges the networking media with the Network layer. Its primary function is to divide the data it receives from the Network layer into frames than can be transmitted by the Physical layer. |
Link layer switch | The least intelligent type of switch because it is nonprogrammable. Layer 2 switches are incapable of transmitting messages outside of the LAN. |
Local account | A windows access account that works only on that one computer. |
Local area network (LAN) | A network of computers and other devices that typically is confined to a relatively small space, such as one building or even one office. Each node on a LAN can communicate directly with others on the same LAN. |
Logical topology | A characteristic of network transmission that reflects the way in which data is transmitted between nodes. A network’s logical topology may differ from its physical topology. |
Loss-tolerant | Transmissions that can tolerate occasional loss of data without compromising the user experience. |
MAC (Media Access Control) | The process by which devices determine which device may access the network at any given time. |
MAC Address | 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. |
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. |
Material safety data sheet (MSDS) | Instructions provided with dangerous substances that explain how to properly handle these substances and how to safely dispose of them. |
Multicast distribution | A client-server model with one server and many clients. |
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 cable, a wire, or the atmosphere. |
Network adapter | The device that enables a ws to connect to the network and communicate with other computers. NICs are manufactured by several different companies and come with a variety of specifications |
Network interface card (NIC) | NICs are also called network adapters. |
Network layer | The third layer in the OSI model. The Network layer, sometimes called the Internet layer, is responsible for moving messages from one node to another until they reach the destination. |
Network operating system (NOS) | The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions. The most popular network operating systems are UNIX, Linux, and Microsoft Windows Server. |
Network services | The resources a network makes available to its users, including applications and the data provided by these applications. |
Node | Any computer or other device on a network that can be addressed on the local network. |
Onboard network port | A port that is integrated into a computer’s motherboard. |
OSHA (Occupational Safety and Health Administration) | The main federal agency charged with regulating safety and health in the workplace. |
OSI (Open Systems Interconnection) | A model for understanding and developing computer-to-computer communication developed in the 1980s by ISO. It divides networking functions among seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. |
Packet | The entire Network layer message, which includes the segment (TCP) or datagram (UDP) from the Transport layer, plus the Network layer header. |
PAN (personal area network) | A network of personal devices, such a cell phone, laptop, and Bluetooth printer. |
Patch panel | A wall- or rack-mounted panel where cables converge in one location. |
Payload | Data that is passed between applications or utility programs and the operating system, and includes control information. |
Peer-to-peer (P2P) network | A network in which every computer can communicate directly with every other computer. By default, no computer on a peer-to-peer network has more authority than another. |
Personal protective equipment (PPE) | Wearable equipment such as goggles that might be required in the workplace to increase safety of workers. |
Physical address | The process by which devices determine which device may access the network at any given time. |
Physical layer | The lowest, or first, layer of the OSI model. The Physical layer is responsible only for sending bits via a wired or wireless transmission. |
Physical topology | The physical layout of the media, nodes, and devices on a network. A physical topology does not specify device types, connectivity methods, or addressing schemes. |
Plenum | The area above the ceiling tile or below the subfloor in a building. |
Point-to-multipoint model | A communications agreement in which one transmitter issues signals to multiple receivers. The receivers may be undefined, as in broadcast transmission, or defined, as in a nonbroadcast transmission. |
Point-to-point model | A data transmission that involves one transmitter and one receiver. |
POP3 (Post Office Protocol, version 3) | The most commonly used form of the Post Office Protocol. |
Port number | The address on a host where an application makes itself available to incoming data. |
Presentation layer | The sixth layer of the OSI model. Protocols in the Presentation layer are responsible for reformatting, compressing, and/or encrypting data in a way that the application on the receiving end can read. |
Print services | The network service that allows printers to be shared by several users on a network. |
Protocol | A standard method or format for communication between network devices. |
Protocol data unit (PDU) | A unit of data at any layer of the OSI model. |
Quality of service (QoS) | The result of specifications for guaranteeing data delivery within a certain period of time after their transmission. |
Rack | An open or enclosed cabinet that holds network devices such as switches, routers, servers, and/or patch panels. |
RDP (Remote Desktop Protocol) | An application layer protocol that uses TCP/IP to transmit graphics and text quickly over a remote client-host connection. RDP also carries session, licensing, and encryption information. |
Remote application | An application that is installed and executed on a server, and is presented to a user working at a client computer. |
Remote Desktop | A feature of windows operating systems that allows a computer to act as a remote host and be controlled from a client also running Windows. |
Remote Desktop Services | A feature of Windows Server 2008 and later editions of Windows Server that allows technicians to manage remote applications. |
Ring topology | A network layout in which each node is connected to the two nearest nodes so that the entire network forms a circle. |
Router | A Layer 3 device that uses logical addressing information to direct data between two or more networks and can help find the best path for traffic to get from one network to another. |
RTP (Real-time Transport Protocol) | An Application layer protocol used with voice and video transmission. |
Scalable – | The property of a network that allows you to add nodes or increase its size easily. |
Secure Shell (SSH) | A connection utility that provides authentication and encryption. With SSH, you can securely log on to a host, execute commands on that host, and copy files to or from that host. SSH encrypts data exchanged throughout the session. |
Segment | (1) A unit of data that results from subdividing a larger protocol data unit. (2) A part of a network. Usually, a segment is composed of a group of nodes that share the same communications channel for all their traffic. |
Session layer | The fifth layer of the OSI model. The Session layer describes how data between applications is synced and recovered if messages don’t arrive intact at the receiving application. |
SFTP (Secure File Transfer Protocol) | A protocol available with the proprietary version of Unlike FTP, SFTP encrypts data before transmitting it. |
SMTP (Simple Mail Transfer Protocol) | The Application layer TCP/IP subprotocol responsible for moving messages from one email server to another. |
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. |
Star topology | A physical topology in which every node on the network is connected through a central device. |
Star-bus topology | A hybrid topology in which groups of work stations are connected in a star fashion to connectivity devices that are networked via a single bus. |
Static electricity | An electrical charge at rest. When that charge is transferred between two bodies, it creates an electrostatic discharge, or ESD. |
Switch | A connectivity device that logically subdivides a network into smaller, individual collision domains. can interpret MAC address information to determine whether to filter (discard) or forward packets it receives. |
TCP (Transmission Control Protocol) | A core protocol of the TCP/IP suit that makes a connection with the end host, checks whether data is received, and resends it if it is not. |
TCP/IP | A suite of networking protocols that includes TCP, IP, UDP, and many others. TCP/IP provides the foundation for data exchange across the Internet. |
Telnet | A terminal emulation protocol used to log on to remote hosts using the TCP/IP protocol. |
Terminal Services | A feature of Windows Server editions prior to Windows Server 2008 that allows technicians to manage remote applications. |
TLS (Transport Layer Security) | A version of SSL standardized by the IETF (Internet Engineering Task Force). TLS uses slightly different encryption algorithms than SSL, but otherwise is very similar to most recent version SSL. |
Topology | How the parts of a whole fit together. |
Trailer | Control information attached to the end of a packet by the Data Link layer protocol. |
Transport layer | The fourth layer of the OSI model. The Transport layer is responsible for transporting Application layer payloads from one application to another. |
Trip hazard | Items such as extension cords or tools lying on the ground in walkways that can cause someone to stumble. |
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. |
Unified communications (UC) | The centralized management of multiple types of network-based communications, such as voice, video, fax, and messaging services. |
Upset failure | Damage that can shorten the life of a component and/or cause intermittent errors. |
Video teleconference (VTC) | An application that allows people to communicate in video or voice. |
VoIP (Voice over IP) | The provision of telephone service over a packet-switched network running the TCP/IP protocol suite. |
WAN (wide area network) | A network that spans a long distance and connects two or more LANs. |