Acronyms become useful when they point to a protocol, device, measurement, failure, or design choice. Use this reference when unfamiliar initials interrupt a guide, practice question, command output, diagram, or troubleshooting conversation. Then return to the surrounding material and apply the term in context.
This list covers 177 Network+ acronyms and terms drawn from the N10-009 objectives and the CertHappens study guides. The page uses a stable Network+ address so later exam versions can add terminology without creating a disconnected reference for every revision.
Context decides the meaning. STP can mean shielded twisted pair or Spanning Tree Protocol. PDU commonly means power distribution unit in a rack, but it can also mean protocol data unit in an OSI discussion. SAN, AP, A, and MAC also need the surrounding scenario.
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Search by acronym, expansion, practical meaning, related term, or exam domain.
Showing all 177 entries.
0-9
- 802.1Q
- IEEE VLAN tagging standard Adds VLAN identification information to Ethernet frames on trunk links so one physical link can carry traffic for multiple VLANs.
- 802.1X
- IEEE port-based network access control Controls access at a wired or wireless network edge by requiring authentication before ordinary traffic is permitted.
A
- A
- Address A DNS record that maps a hostname to an IPv4 address.
- AAA
- Authentication, Authorization, and Accounting A framework that verifies identity, decides permitted actions, and records activity.
- AAAA
- IPv6 address record A DNS record that maps a hostname to an IPv6 address.
- ACL
- Access Control List A set of rules that permits or denies access to a resource, network path, or object.
- AH
- Authentication Header An IPsec component that provides integrity and origin authentication without encrypting the payload.
- AP
- Access Point A wireless device that connects Wi-Fi clients to a wired or distributed network.
- API
- Application Programming Interface A defined way for software components or services to exchange requests and data.
- APIPA
- Automatic Private Internet Protocol Addressing Windows terminology for automatic IPv4 link-local addressing in 169.254.0.0/16 when a client cannot obtain a normal DHCP lease.
- ARP
- Address Resolution Protocol A protocol that maps an IPv4 address to a local network hardware address.
- AUP
- Acceptable Use Policy A policy that defines permitted and prohibited use of organizational systems and data.
B
- BGP
- Border Gateway Protocol The routing protocol used to exchange reachability information between autonomous systems on the internet.
- BNC
- Bayonet Neill-Concelman A twist-lock coaxial connector found in legacy networking, video, and test equipment.
- BSSID
- Basic Service Set Identifier The identifier for one wireless basic service set, commonly the MAC address of a specific access-point radio.
- BYOD
- Bring Your Own Device A model that permits personally owned devices to access organizational resources.
C
- CAM
- Content-addressable Memory The switch memory table that associates learned MAC addresses with ports and VLANs for frame forwarding.
- CDN
- Content Delivery Network A distributed group of servers that places content closer to users to reduce latency and origin-server load.
- CDP
- Cisco Discovery Protocol A Cisco discovery protocol that advertises neighboring device identity and interface information on the local link.
- CIA
- Confidentiality, Integrity, and Availability Three foundational security goals: prevent unauthorized disclosure, preserve trustworthy data, and keep services usable.
- CIDR
- Classless Inter-Domain Routing Prefix-length notation and route aggregation that describe networks without relying on legacy address classes.
- CLI
- Command-line Interface A text-based interface used to enter commands and inspect device or operating-system output.
- CNAME
- Canonical Name A DNS alias record that points one name to another canonical hostname rather than directly to an address.
- CPU
- Central Processing Unit The processor that executes instructions. High utilization can affect control-plane work, services, or device responsiveness.
- CRC
- Cyclic Redundancy Check An error-detection value checked on received frames. Rising CRC errors often point to cabling, interference, optic, or duplex problems.
D
- DAC
- Direct Attach Copper A short twinaxial copper cable assembly with integrated transceiver ends, commonly used for nearby high-speed switch or server connections.
- DAS
- Direct-attached Storage Storage attached directly to one host rather than accessed through a file or storage network.
- DCI
- Data Center Interconnect Connectivity between data centers, often carrying routed traffic or extended logical networks between sites.
- DDoS
- Distributed Denial-of-Service A denial-of-service attack launched from many systems at once to exhaust a target's resources.
- DHCP
- Dynamic Host Configuration Protocol A protocol that automatically assigns IP configuration to network clients.
- DLP
- Data Loss Prevention Controls that identify sensitive information and restrict unauthorized transfer or exposure.
- DNS
- Domain Name System The distributed service that maps names to records such as IP addresses and mail servers.
- DNSSEC
- Domain Name System Security Extensions Extensions that add signed DNS data so resolvers can validate integrity and origin.
- DoH
- DNS over HTTPS Carries DNS queries inside HTTPS, protecting the resolver traffic from simple observation or modification in transit.
- DoS
- Denial-of-Service An attack or condition that prevents legitimate users from accessing a service.
- DoT
- DNS over TLS Carries DNS queries over a dedicated TLS-protected transport, normally TCP port 853.
- DR
- Disaster Recovery Planning and technical arrangements used to restore systems, data, and services after a disruptive event.
E
- EAPoL
- Extensible Authentication Protocol over LAN The local-link framing used to carry 802.1X authentication messages between a supplicant and an authenticator.
- EIGRP
- Enhanced Interior Gateway Routing Protocol A dynamic interior routing protocol that selects paths using a composite metric and exchanges routes within an organization.
- EOL
- End-of-Life The point when a product reaches the end of its planned life cycle. Availability, updates, and replacement planning may change.
- EOS
- End-of-Support The point when a vendor stops providing some or all support, fixes, or updates for a product or release.
- ESP
- Encapsulating Security Payload An IPsec component that can provide encryption, integrity, and authentication for network traffic.
- ESSID
- Extended Service Set Identifier A name associated with an extended wireless service spanning multiple access points. In ordinary use, SSID is the more common term.
- EULA
- End User License Agreement A contract that defines how software may be installed, used, and distributed.
F
- FC
- Fibre Channel A high-speed storage networking technology commonly used to carry block-storage traffic in a SAN.
- FHRP
- First Hop Redundancy Protocol A family of gateway-redundancy protocols that presents a virtual default-gateway address backed by multiple routers.
- FTP
- File Transfer Protocol A legacy file-transfer protocol that does not encrypt credentials or content by default.
G
- GDPR
- General Data Protection Regulation A European Union privacy regulation governing personal-data processing and individual rights.
- GRE
- Generic Routing Encapsulation A tunneling protocol that encapsulates one network-layer packet inside another but does not provide encryption by itself.
- GUI
- Graphical User Interface A graphical interface used to configure or monitor a system through windows, forms, menus, and visual controls.
H
- HTTP
- Hypertext Transfer Protocol The application protocol used for web requests and responses without built-in transport encryption.
- HTTPS
- Hypertext Transfer Protocol Secure HTTP protected by TLS to provide encrypted and authenticated transport.
I
- IaaS
- Infrastructure as a Service A cloud model in which the provider supplies infrastructure while the customer manages operating systems, applications, and much of the configuration.
- IaC
- Infrastructure as Code The management of infrastructure through versioned, repeatable configuration files or templates.
- IAM
- Identity and Access Management Processes and technologies for creating identities, authenticating users, and controlling access.
- ICMP
- Internet Control Message Protocol A network protocol used for diagnostics and control messages, including many ping and error responses.
- ICMPv6
- Internet Control Message Protocol for IPv6 IPv6 control messaging used for errors, diagnostics, neighbor discovery, router discovery, and other essential IPv6 functions.
- ICS
- Industrial Control System Technology used to monitor and control industrial processes and physical equipment.
- IDF
- Intermediate Distribution Frame A local telecommunications room that distributes cabling and network access within part of a building and normally uplinks to the MDF.
- IDS
- Intrusion Detection System A control that identifies suspicious activity and generates alerts without necessarily blocking traffic.
- IIoT
- Industrial Internet of Things Connected industrial sensors, controllers, and equipment whose availability, safety, and long service life affect network design.
- IKE
- Internet Key Exchange A protocol used to negotiate security associations and keys for IPsec.
- IoT
- Internet of Things Network-connected devices that sense, process, or control physical environments, often with limited resources and long lifecycles.
- IP
- Internet Protocol The network-layer protocol used to address and route packets between systems.
- IPAM
- IP Address Management A system for tracking IP networks, addresses, assignments, reservations, DNS relationships, and address-space usage.
- IPS
- Intrusion Prevention System A control placed inline to detect and block suspicious traffic.
- IPsec
- Internet Protocol Security A suite of protocols that protects IP traffic through authentication, integrity, and optional encryption.
- IPv4
- Internet Protocol version 4 The 32-bit Internet Protocol address format written as four decimal octets, such as 192.0.2.10.
- IPv6
- Internet Protocol version 6 The 128-bit Internet Protocol address format designed for a much larger address space and modern autoconfiguration behavior.
- IS-IS
- Intermediate System to Intermediate System A link-state interior routing protocol that exchanges topology information and calculates shortest paths within an autonomous system.
L
- LACP
- Link Aggregation Control Protocol The standards-based protocol used to negotiate and maintain compatible links inside an Ethernet link-aggregation group.
- LAN
- Local Area Network A network covering a limited area such as an office, home, or campus segment.
- LC
- Local Connector A small fiber-optic connector commonly used on modern transceivers and patch panels.
- LDAP
- Lightweight Directory Access Protocol A protocol used to query and manage directory services.
- LDAPS
- Lightweight Directory Access Protocol over TLS LDAP protected by TLS, commonly associated with TCP port 636. Modern deployments may also use LDAP with StartTLS.
- LLDP
- Link Layer Discovery Protocol A vendor-neutral local-link discovery protocol that advertises device, interface, VLAN, power, and other neighbor information.
M
- MAC
- Media Access Control The data-link layer function and hardware addressing used on local networks.
- MDF
- Main Distribution Frame The main telecommunications room where external services, backbone cabling, and major distribution connections commonly meet.
- MDI-X
- Medium Dependent Interface Crossover An Ethernet port wiring arrangement that swaps transmit and receive pairs. Auto MDI-X lets modern ports correct this automatically.
- MFA
- Multifactor Authentication Authentication that requires evidence from at least two different factor categories.
- MIB
- Management Information Base A structured collection of objects and identifiers that an SNMP manager can read or modify on a managed device.
- MPO
- Multifiber Push On A multi-fiber connector that terminates several optical fibers in one compact connection.
- MTBF
- Mean Time Between Failures The average operating time between repairable failures, often used as a reliability measure.
- MTTR
- Mean Time to Repair The average time required to restore a service after failure. Some organizations use the same initials for mean time to repair, so read the surrounding definition.
- MTU
- Maximum Transmission Unit The largest network-layer packet or link-layer payload an interface can carry without fragmentation or another accommodation.
- MX
- Mail Exchange A DNS record that identifies the mail server responsible for accepting email for a domain and includes a preference value.
N
- NAC
- Network Access Control Technology that evaluates users or devices before and during network access, then permits, restricts, or isolates them.
- NAS
- Network-attached Storage A networked storage system that provides file-level access through protocols such as SMB or NFS.
- NAT
- Network Address Translation A network function that rewrites IP address information between address spaces.
- NAT64
- Network Address Translation 64 A translation method that allows IPv6-only clients to communicate with IPv4 services, commonly with a DNS64 function.
- NFV
- Network Functions Virtualization Running network functions such as routing, firewalling, or load balancing as software rather than only on dedicated appliances.
- NIC
- Network Interface Card The hardware or virtual adapter that connects a system to a network and supplies link-layer functions such as a MAC address.
- NS
- Name Server A DNS record that identifies the authoritative name servers for a zone or delegated domain.
- NTP
- Network Time Protocol A protocol used to synchronize system clocks, which is important for logs, authentication, and investigations.
- NTS
- Network Time Security A security extension for NTP that authenticates time synchronization and helps resist tampering and spoofed time sources.
O
- OS
- Operating System The software layer that manages hardware, processes, memory, files, and system services.
- OSI
- Open Systems Interconnection A seven-layer reference model used to organize networking functions and structure troubleshooting reasoning.
- OSPF
- Open Shortest Path First A link-state interior routing protocol that calculates shortest paths from exchanged topology information and uses areas for scale.
- OT
- Operational Technology Hardware and software that monitors or controls physical processes, equipment, and industrial operations.
P
- PaaS
- Platform as a Service A cloud model in which the provider manages the underlying platform while the customer deploys applications and data.
- PAT
- Port Address Translation A form of NAT that maps many internal connections to one public address by tracking transport-layer ports.
- PCI DSS
- Payment Card Industry Data Security Standard An industry security standard for organizations that store, process, or transmit payment-card data.
- PDU
- Power Distribution Unit A device that distributes electrical power to rack equipment. Do not confuse it with protocol data unit in an OSI discussion.
- PKI
- Public Key Infrastructure The people, policies, services, keys, and certificates used to establish and manage public-key trust.
- PoE
- Power over Ethernet Supplies electrical power and Ethernet data over compatible copper cabling to devices such as access points, phones, and cameras.
- PSK
- Pre-shared Key A secret configured on participating systems before secure communication begins.
- PTP
- Precision Time Protocol A time-synchronization protocol designed for greater precision than ordinary NTP in supported networks and applications.
- PTR
- Pointer A DNS reverse-lookup record that maps an IP address representation back to a hostname.
Q
- QoS
- Quality of Service Classification, marking, queuing, shaping, and related policies used to manage delay, loss, and priority for different traffic.
- QSFP
- Quad Small Form-factor Pluggable A compact, high-density transceiver form factor commonly used for higher-speed links and breakout connections.
R
- RADIUS
- Remote Authentication Dial-In User Service A protocol that centralizes authentication, authorization, and accounting for network access.
- RBAC
- Role-based Access Control An access model that assigns permissions to job roles and then assigns users to those roles.
- RDP
- Remote Desktop Protocol A Microsoft protocol for interactive remote desktop sessions.
- RFC
- Request for Comments A numbered publication in the Internet standards and engineering series. Some RFCs define standards, while others are informational.
- RFID
- Radio-frequency Identification A technology that uses radio signals to identify tags, cards, assets, or devices.
- RIP
- Routing Information Protocol A distance-vector interior routing protocol that uses hop count and has limited scale compared with modern alternatives.
- RJ
- Registered Jack A registered-jack designation used in connector names. Network cabling commonly uses the familiar RJ45-style modular connector.
- RPO
- Recovery Point Objective The maximum acceptable amount of data loss measured backward in time from a disruption.
- RSTP
- Rapid Spanning Tree Protocol A faster-converging evolution of spanning tree that moves switch ports through simplified states after topology changes.
- RTO
- Recovery Time Objective The maximum acceptable time for restoring a service after disruption. The phrase return to operations can be a useful memory cue, but the Security+ term is Recovery Time Objective.
- RTP
- Real-time Transport Protocol Carries real-time audio or video media, commonly using negotiated UDP ports while a signaling protocol such as SIP manages the session.
- RX
- Receiver The receive side of a link, optic, or interface. Transposed transmit and receive paths can prevent link establishment.
S
- SaaS
- Software as a Service A cloud model in which the provider operates the application while the customer manages users, data, and selected configuration.
- SAML
- Security Assertion Markup Language An XML-based standard used to exchange authentication and authorization assertions, commonly for federation and single sign-on.
- SAN
- Storage Area Network A dedicated storage network that presents block-level storage to servers, commonly using Fibre Channel or iSCSI.
- SASE
- Secure Access Service Edge A cloud-delivered architecture that combines network connectivity and security services near users and resources.
- SC
- Subscriber Connector A push-pull fiber connector larger than LC and still found in patch panels, carrier facilities, and older installations.
- SCADA
- Supervisory Control and Data Acquisition Systems that monitor and control industrial processes across distributed locations.
- SD-WAN
- Software-defined Wide Area Network A centrally managed WAN architecture that selects paths and applies policy across multiple links.
- SDN
- Software-defined Networking A network architecture that separates centralized control logic from packet forwarding.
- SFP
- Small Form-factor Pluggable A modular transceiver form factor used for copper or fiber links at supported speeds and distances.
- SFTP
- Secure File Transfer Protocol A secure file-transfer protocol that runs over SSH. It is different from FTPS.
- SIEM
- Security Information and Event Management A platform that collects, correlates, searches, and alerts on logs and security events.
- SIP
- Session Initiation Protocol A signaling protocol used to establish, modify, and end voice or multimedia sessions; the media commonly travels separately over RTP.
- SLA
- Service-level Agreement A contract or commitment that defines measurable service expectations such as uptime and response times.
- SLAAC
- Stateless Address Autoconfiguration An IPv6 mechanism that lets a host form an address from router-advertisement information without a stateful address lease.
- SMB
- Server Message Block A protocol used for shared files, printers, and related services, especially in Windows environments.
- SMTP
- Simple Mail Transfer Protocol The standard protocol for sending and relaying email.
- SMTPS
- Simple Mail Transfer Protocol Secure SMTP protected with TLS. The term may refer to implicit TLS or, informally, to secure mail submission depending on context.
- SNMP
- Simple Network Management Protocol A protocol used to monitor and manage network devices and report operational information.
- SOA
- Start of Authority The DNS record that identifies key authority and timing information for a zone, including the primary server and serial number.
- SQL
- Structured Query Language A language used to create, query, and manage relational databases.
- SSE
- Security Service Edge Cloud-delivered security services such as secure web access, cloud access security, and zero-trust access without the WAN transport portion of SASE.
- SSH
- Secure Shell A protocol for encrypted remote administration, command execution, tunneling, and file transfer.
- SSID
- Service Set Identifier The human-readable wireless network name advertised or configured for a Wi-Fi service.
- SSL
- Secure Sockets Layer A retired predecessor to TLS. Modern secure services should negotiate supported TLS versions rather than legacy SSL.
- SSO
- Single Sign-On An identity arrangement that lets a user authenticate once and access multiple connected services.
- ST
- Straight Tip A bayonet-style fiber connector used in some legacy campus, industrial, and test environments.
- STP
- Shielded Twisted Pair Copper cabling with shielding that helps reduce electromagnetic interference when correctly selected, grounded, and installed.
- STP
- Spanning Tree Protocol A Layer 2 loop-prevention protocol that selects a root bridge and blocks redundant paths until they are needed.
- SVI
- Switch Virtual Interface A logical Layer 3 interface associated with a VLAN, used for management or inter-VLAN routing on a multilayer switch.
T
- TACACS+
- Terminal Access Controller Access-Control System Plus A protocol commonly used for centralized administration access to network devices, with separate authentication, authorization, and accounting functions.
- TCP
- Transmission Control Protocol A connection-oriented transport protocol that provides ordered delivery, acknowledgments, retransmission, and flow control.
- TCP/IP
- Transmission Control Protocol/Internet Protocol The practical protocol suite built around IP addressing and transports such as TCP and UDP, rather than a single protocol.
- TFTP
- Trivial File Transfer Protocol A minimal UDP file-transfer protocol without the authentication and features of FTP or SFTP, often used for boot or configuration files.
- TLS
- Transport Layer Security A protocol that protects network communication with encryption, integrity, and certificate-based authentication.
- TTL
- Time to Live A field that limits how many routed hops an IP packet can traverse, preventing packets from circulating indefinitely.
- TX
- Transmitter The transmit side of a link, optic, or interface. A TX/RX reversal or incompatible optic can prevent communication.
- TXT
- Text A DNS record containing text data, commonly used for domain verification and email-policy information.
U
- UDP
- User Datagram Protocol A connectionless transport protocol with low overhead and no built-in delivery guarantee.
- UPS
- Uninterruptible Power Supply A battery-backed device that supplies short-term power and conditions electricity during an outage or fluctuation.
- URL
- Uniform Resource Locator A URI that identifies a resource by location and access method.
- USB
- Universal Serial Bus A standard for connecting peripherals, storage, power, and data interfaces.
- UTM
- Unified Threat Management A security appliance that combines several controls such as firewalling, intrusion prevention, filtering, and malware protection.
- UTP
- Unshielded Twisted Pair Copper twisted-pair cabling without an overall shield, widely used for Ethernet in ordinary office environments.
V
- VIP
- Virtual IP A logical IP address associated with a redundant gateway, load balancer, cluster, or service rather than one fixed interface.
- VLAN
- Virtual Local Area Network A logical Layer 2 network segment created on switching infrastructure.
- VLSM
- Variable Length Subnet Mask Using different prefix lengths within an address plan so each subnet receives an appropriately sized block.
- VoIP
- Voice over IP Voice and related signaling carried over IP networks, with quality affected by latency, jitter, loss, and prioritization.
- VPC
- Virtual Private Cloud A logically isolated cloud network in which customers define subnets, routes, and security controls.
- VPN
- Virtual Private Network An encrypted tunnel that protects traffic across an untrusted network.
- VXLAN
- Virtual Extensible LAN An overlay encapsulation that carries Layer 2 segments across a Layer 3 underlay using a larger logical segment identifier.
W
- WAN
- Wide Area Network A network that connects systems across large geographic areas or multiple sites.
- WLAN
- Wireless Local Area Network A local network that uses Wi-Fi radio links instead of only wired Ethernet connections.
- WPA
- Wi-Fi Protected Access A family of Wi-Fi security standards. WPA2 and WPA3 provide stronger modern protections than the original WPA design.
- WPS
- Wi-Fi Protected Setup A convenience method for enrolling devices in a Wi-Fi network. PIN-based WPS has well-known security concerns and is often disabled.
Z
- ZTA
- Zero Trust Architecture An architecture that continuously evaluates identity, device, resource, and policy signals instead of trusting a user because of network location.
No matching terms were found. Try the full phrase, a nearby protocol, or a broader networking concept.
Use acronyms as troubleshooting clues
Expanding the letters is only the first step. CRC should lead to a frame-integrity error and a physical-link investigation. RPO should lead to acceptable data loss, while RTO should lead to acceptable downtime. CIDR should lead to prefix length, route aggregation, or subnet boundaries rather than legacy address classes.
When terms look similar, compare the job each one performs. LLDP and CDP discover directly connected neighbors. DNSSEC validates signed DNS data, while DoH and DoT protect DNS transport. RADIUS commonly supports network access, while TACACS+ commonly supports administration of network devices. The expansion helps you decode the initials; the operational difference earns the answer.
Official reference
The published N10-009 objectives include an acronym appendix. Use the current Network+ exam objectives as the final scope checklist for the exam version you are preparing to take.