Technology definitions

30 technology terms from Achievable exam prep courses, each defined in plain language with links into the course textbook.

• Access control list (ACL)An access control list (ACL) is an ordered set of permit and deny rules that a router or switch applies to network traffic. Packets are checked against the rules top-down, and any packet that matches no rule is dropped by an implicit deny at the end.
• Big dataBig data refers to data sets so large, fast-moving, and varied that traditional processing tools cannot handle them, commonly characterized by the "Vs": volume, velocity, variety, and veracity.
• Business intelligenceBusiness intelligence (BI) is the set of technologies and processes that transform raw data into meaningful information for decision-making. It spans collecting, storing, analyzing, and presenting data through reports and dashboards.
• CDP and LLDPCDP (Cisco Discovery Protocol) and LLDP (Link Layer Discovery Protocol) are Layer 2 protocols that let directly connected network devices advertise and learn information about each other, such as device name, port, and capabilities. CDP is Cisco proprietary, while LLDP is an open IEEE standard.
• DHCP snooping and Dynamic ARP InspectionDHCP snooping is a Layer 2 switch security feature that blocks rogue DHCP servers by filtering DHCP messages on untrusted ports. Dynamic ARP Inspection (DAI) builds on it, using the snooping binding table to drop spoofed ARP packets.
• Domain Name System (DNS)The Domain Name System (DNS) is the hierarchical, distributed naming system that translates human-readable domain names like example.com into the IP addresses computers use to route traffic.
• Dynamic Host Configuration Protocol (DHCP)DHCP (Dynamic Host Configuration Protocol) is a network protocol that automatically assigns IP addresses and related settings — subnet mask, default gateway, and DNS servers — to devices joining a network, leasing each address for a limited time.
• Enterprise resource planning (ERP)Enterprise resource planning (ERP) is business software that integrates a company's core functions — accounting, human resources, supply chain, manufacturing, and sales — into a single system built on one shared database.
• EtherChannel and LACPAn EtherChannel bundles multiple physical Ethernet links between two switches into a single logical link, combining their bandwidth and providing redundancy. LACP is the standards-based protocol that negotiates the bundle automatically.
• Exploratory data analysisExploratory data analysis (EDA) is the practice of examining a dataset with summary statistics and visualizations to understand its structure, spot patterns and outliers, and generate hypotheses before formal modeling or testing.
• Firewalls and intrusion prevention systemsFirewalls and intrusion prevention systems (IPS) are network security devices that control and inspect traffic. A firewall permits or denies traffic based on configured rules, while an IPS analyzes traffic for attack patterns and blocks malicious activity in real time.
• First Hop Redundancy Protocols (FHRP)First Hop Redundancy Protocols (FHRPs) let multiple routers share a virtual IP and MAC address so hosts keep a working default gateway even if a router fails. The main FHRPs are HSRP, VRRP, and GLBP.
• IP addressAn IP address is a numerical identifier assigned to each device on a network so traffic can be routed to it. IPv4 addresses are 32-bit numbers written as four octets (like 192.168.1.10); IPv6 addresses are 128 bits.
• IPv6IPv6 is the most recent version of the Internet Protocol, using 128-bit addresses written in hexadecimal to provide a vastly larger address space than IPv4, along with built-in features like stateless address autoconfiguration.
• Network Address Translation (NAT)Network Address Translation is a router function that rewrites IP addresses in packet headers as traffic passes between networks. It lets many devices with private IP addresses share a smaller number of public addresses when reaching the internet.
• Network Time Protocol (NTP)The Network Time Protocol (NTP) is a networking protocol that synchronizes the clocks of devices across a network to a common time reference. It runs over UDP port 123 and organizes time sources into a hierarchy of strata.
• Network topologyNetwork topology is the arrangement of devices and the links between them in a network. Physical topology describes how the cabling is actually run, while logical topology describes the path data takes through the network regardless of the wiring.
• Port security (networking)Port security is a Layer 2 switch feature that restricts which devices may send traffic on an interface by limiting and learning source MAC addresses. When a violation occurs, the switch can shut down the port, drop the traffic, or log the event.
• Quality of Service (QoS)Quality of Service is a set of network tools that prioritize some traffic over other traffic when a link is congested. It manages bandwidth, delay, jitter, and packet loss so that sensitive applications such as voice and video stay usable.
• Simple Network Management Protocol (SNMP)SNMP is an application-layer protocol that lets a management station monitor and configure network devices such as routers, switches, and servers. Agents on each device expose data through a MIB, and the manager reads or sets those values over UDP.
• Software-defined networking (SDN)Software-defined networking (SDN) is an architecture that separates a network device's control plane from its data plane and centralizes control in a software controller. Administrators then configure the whole network programmatically instead of device by device.
• Spanning Tree Protocol (STP)The Spanning Tree Protocol (STP) is a Layer 2 protocol that prevents switching loops in networks with redundant links. It blocks selected ports so that only one active path exists between any two devices, then reactivates a blocked path if the primary link fails.
• Static routingStatic routing is the practice of manually configuring routes in a router's routing table instead of learning them from a routing protocol. The routes never change on their own, so an administrator must update them when the network topology changes.
• SyslogSyslog is a standard protocol that network devices use to send event and status messages to a central logging server. It gives administrators one place to review what happened across routers, switches, firewalls, and servers.
• System development life cycle (SDLC)The system development life cycle is the structured sequence of phases an organization follows to plan, build, test, deploy, and maintain an information system. It provides a repeatable framework with defined deliverables and control points at each stage.
• TCP vs. UDPTCP and UDP are the two main transport layer protocols. TCP is connection-oriented and reliable, retransmitting lost data and delivering it in order, while UDP is connectionless and unreliable, trading those guarantees for lower overhead and latency.
• TCP/IP modelThe TCP/IP model is the four-layer framework that describes how data moves across the internet, consisting of the application, transport, internet, and network access layers. It is the practical model real networks are built on.
• Transport layerThe transport layer is Layer 4 of the OSI model, responsible for end-to-end communication between applications on different hosts. It uses port numbers to direct traffic to the right application and provides either reliable delivery with TCP or low-overhead delivery with UDP.
• Virtual private network (VPN)A virtual private network creates a secure, encrypted connection across an untrusted network such as the internet, allowing remote sites or users to exchange data as if they were on the same private network. The encrypted path is commonly described as a tunnel.
• Wireless LAN (WLAN)A wireless LAN is a local area network that connects devices over radio waves instead of cables, using the IEEE 802.11 standards. Access points bridge wireless clients onto the wired network so they behave like any other LAN device.