CompTIA Network+ Certification Exam Glossary

Definitions and pro-tips for the N10-009 certification.

C

Cable Types

Networking utilizes various cable types, including twisted-pair (Cat5e, Cat6, Cat6a) and fiber optic. Twisted-pair cables transmit data via electrical signals, while fiber optic uses light. Cable selection depends on bandwidth requirements, distance limitations, and environmental factors.

Channel Bonding

Channel bonding, also known as link aggregation, combines multiple network channels—typically wireless—to create a single, higher-bandwidth connection. This increases data throughput and improves network reliability by distributing traffic across multiple links.

Classless Inter-Domain Routing (CIDR)

Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and routing that replaces the older class-based system. It uses variable-length subnet masking (VLSM) to allow for more flexible and efficient use of the available IPv4 address space.

Cloud Access Security Broker (CASB)

Cloud Access Security Broker (CASB) is a software tool or service that sits between cloud service consumers and cloud service providers. It enforces security, compliance, and governance policies for data moving to and from the cloud.

Cloud Computing

Cloud computing delivers on-demand access to computing resources—servers, storage, databases, networking, software, analytics—over the internet. This model enables scalability, cost efficiency, and resource optimization by shifting infrastructure management from on-premises to a third-party provider.

Coaxial Cable

Coaxial cable transmits data via a central conductor surrounded by insulation and shielding, minimizing signal interference. Historically used for cable TV and 10BASE2 networks, it offers moderate bandwidth and is susceptible to signal degradation over long distances.

Control and Provisioning of Wireless Access Points (CAPWAP)

Control and Provisioning of Wireless Access Points (CAPWAP) is a standard protocol used by a wireless LAN controller (WLC) to manage a group of lightweight access points. It creates a tunnel to encapsulate control and data traffic, centralizing the management of the wireless network.

D

Dense Wavelength Division Multiplexing (DWDM)

Dense Wavelength Division Multiplexing (DWDM) is an optical multiplexing technology used to increase bandwidth over existing fiber optic cables. It works by combining multiple signals at different wavelengths of laser light onto a single fiber strand.

DHCP

Dynamic Host Configuration Protocol automates IP address assignment and network configuration for devices on a TCP/IP network. It leases IP addresses, subnet masks, default gateways, and DNS server addresses, reducing administrative overhead and potential IP conflicts. Proper DHCP function is critical for network connectivity.

DHCP Snooping

DHCP Snooping is a Layer 2 security feature that acts like a firewall between untrusted hosts and trusted DHCP servers. It prevents rogue DHCP servers from assigning incorrect IP addresses to clients by filtering unauthorized DHCP messages.

DMZ

A Demilitarized Zone (DMZ) is a network segment positioned between an organization’s internal network and an untrusted external network, like the internet. It hosts services—web, email, DNS—intended for external access, isolating them from the internal network to mitigate security risks.

DNS

The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, or any resource connected to the Internet or a private network. It translates human-readable domain names (e.g., google.com) into IP addresses, enabling network communication. DNS relies on a system of DNS servers.

Dynamic ARP Inspection (DAI)

Dynamic ARP Inspection (DAI) is a security feature that validates Address Resolution Protocol (ARP) packets in a network. It intercepts and discards ARP packets with invalid IP-to-MAC address bindings to prevent ARP poisoning and spoofing attacks.

I

Internet Control Message Protocol (ICMP)

Internet Control Message Protocol (ICMP) is a supporting protocol in the IP suite used by network devices to send error messages and operational information. It is most commonly utilized by tools like ping and traceroute to diagnose connectivity issues and determine network reachability.

Internet Group Management Protocol (IGMP)

Internet Group Management Protocol (IGMP) is a communications protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships. It allows a device to inform its local router that it wants to receive traffic destined for a specific multicast group.

Intrusion Detection System (IDS)

An Intrusion Detection System (IDS) is a security tool that monitors network traffic for signs of malicious activity or policy violations. It typically operates as a passive device, alerting administrators to potential threats without actively blocking the traffic.

Intrusion Prevention System (IPS)

An Intrusion Prevention System (IPS) is an active security appliance that monitors network traffic and automatically takes action to block detected threats. Unlike an IDS, an IPS sits in-line with traffic to drop malicious packets in real-time.

IP Address

An Internet Protocol (IP) address is a numerical label assigned to each device participating in a computer network utilizing the Internet Protocol for communication. IPv4 addresses are 32-bit, while IPv6 addresses are 128-bit, providing a significantly larger address space.

IPsec

Internet Protocol Security (IPsec) is a suite of protocols used to secure IP communications by authenticating and encrypting each IP packet. It provides data confidentiality, integrity, and authentication at the network layer. IPsec is commonly used for establishing secure VPN connections and protecting sensitive network traffic.

IPv6

IPv6 is the latest version of the Internet Protocol, utilizing 128-bit addresses to overcome the limitations of IPv4’s 32-bit address space. It offers enhanced security features, simplified address configuration, and improved support for mobile devices and the Internet of Things.

L

Latency

Latency measures the delay in milliseconds for data transmission between network endpoints. It represents the time required for a packet to travel from source to destination. High latency impacts interactive applications, causing noticeable delays and reduced responsiveness. It is a critical performance metric for network troubleshooting.

Leaf-Spine Architecture

Leaf-Spine Architecture is a two-tier network topology commonly used in modern data centers to optimize east-west traffic. Every leaf switch connects to every spine switch, ensuring predictable latency and high bandwidth across the fabric.

Lightweight Directory Access Protocol (LDAP)

Lightweight Directory Access Protocol (LDAP) is an open, vendor-neutral industry standard application protocol used for accessing and maintaining distributed directory information services. It is commonly used for centralized authentication and user management.

Link Aggregation Control Protocol (LACP)

Link Aggregation Control Protocol (LACP) is a vendor-neutral standard used to bundle multiple physical network links into a single logical link. This process, known as link aggregation, increases available bandwidth and provides redundancy by automatically managing the failover between the combined physical ports.

Load Balancing

Load balancing distributes network traffic across multiple servers to maximize throughput, minimize response time, and prevent overload. This technique enhances application availability and reliability by ensuring continuous service even if one server fails. It’s a critical component of scalable network infrastructure.

Loop Prevention

Loop prevention mechanisms mitigate broadcast storms caused by redundant network paths. These mechanisms detect and disable redundant links, ensuring data packets do not circulate endlessly, consuming bandwidth and degrading network performance. Effective loop prevention is critical for network stability.

Loopback Address

The loopback address, 127.0.0.1, is a reserved IP address used for internal testing of the TCP/IP protocol stack on a host. It allows applications to communicate with themselves without utilizing physical network interfaces, verifying local network configuration.

M

MAC Address

A Media Access Control (MAC) address is a unique 48-bit hardware identifier assigned to a network interface card (NIC). It operates at the Data Link Layer (Layer 2) and is used for communication within a local network segment, enabling frame delivery to specific devices.

MIMO

Multiple-Input and Multiple-Output (MIMO) is a wireless technology utilizing multiple antennas at both the transmitter and receiver to increase data throughput and range. By exploiting multipath propagation, MIMO creates multiple spatial streams, effectively multiplying the capacity of the wireless link without requiring additional bandwidth.

MTU

Maximum Transmission Unit (MTU) specifies the largest packet size permissible for transmission over a network. When a packet exceeds the MTU, it undergoes fragmentation, potentially impacting network performance. Standard Ethernet MTU is 1500 bytes.

Multicast

Multicast is a one-to-many network communication method delivering data simultaneously to a selected group of recipients. Utilizing dedicated multicast IP addresses, it efficiently distributes data, reducing network congestion compared to sending individual unicast streams.

Multiprotocol Label Switching (MPLS)

Multiprotocol Label Switching (MPLS) is a routing technique that directs data from one node to the next based on short path labels rather than long network addresses. This allows for faster packet forwarding and the creation of virtual private networks (VPNs) across a service provider's core.

N

NAT

Network Address Translation modifies IP address information while in transit, typically to allow multiple devices on a private network to share a single public IP address. It enhances security by hiding internal network addresses and conserves public IPv4 address space. NAT operates at the network layer.

NetFlow

NetFlow is a protocol used to collect IP network traffic as it enters or exits an interface. It provides detailed visibility into traffic patterns, including source and destination IPs, ports, and protocol, which is essential for capacity planning and security analysis.

Network Access Control (NAC)

Network Access Control (NAC) is a security solution that enforces policy-based access to a network. It evaluates the 'posture' of a connecting device—checking for updated antivirus or OS patches—before granting access to specific network segments.

Network Address Translation (NAT)

Network Address Translation (NAT) modifies IP address information in packet headers, enabling multiple devices on a private network to share a single public IP address. This conserves public IP addresses and provides a basic level of security by hiding internal network structure. It operates at the network layer.

Network Baseline

A network baseline is a documented set of performance metrics—bandwidth utilization, latency, error rates—established during normal network operation. It serves as a reference point for identifying deviations, diagnosing performance issues, and validating network changes.

Network Configuration Management

Network Configuration Management (NCM) encompasses the systematic process of tracking, controlling, and implementing changes to network device configurations. This includes documentation, version control, automated backups, and compliance auditing to ensure network stability, security, and consistent performance across the infrastructure.

Network Documentation

Network documentation comprises comprehensive records of a network’s design, configuration, and operational procedures. This includes network diagrams, IP address schemes, configuration files, and maintenance logs. Accurate documentation is crucial for efficient management, troubleshooting, and disaster recovery planning.

Network Forensics

Network Forensics is the investigation and analysis of network traffic and logs to identify the cause of security incidents, policy violations, or performance issues. It involves packet capture, data analysis, and reconstruction of events to determine the scope and impact of an incident.

Network Monitoring

Network monitoring systematically tracks network device and link performance, identifying faults, bottlenecks, and security threats. It employs tools analyzing metrics like bandwidth utilization, latency, and packet loss to ensure optimal network operation and proactive issue resolution.

Network Protocols

Network protocols are standardized rules defining how devices exchange data across a network. These rules govern addressing, formatting, error detection, and transmission speeds. Common examples include TCP/IP, UDP, HTTP, and DNS, each serving specific communication functions within a network architecture.

Network Segmentation

Network segmentation divides a network into smaller, isolated segments. This enhances security by limiting the impact of breaches, improves performance by reducing broadcast domains, and simplifies network management through focused policies and access controls. VLANs and firewalls are common segmentation tools.

Network Services

Network services are applications enabling specific network functionalities for clients. These include resource sharing, communication, and remote access. Common examples are DNS, DHCP, and web services, each utilizing specific ports and protocols to deliver their respective functions across a network infrastructure.

Network Time Protocol (NTP)

Network Time Protocol (NTP) synchronizes clocks across networked devices. Utilizing Coordinated Universal Time (UTC), NTP ensures accurate timestamps for logging, security auditing, and transaction ordering. It operates on UDP ports 123, querying time servers to maintain precision.

Network Topology

Network topology defines the physical or logical arrangement of network nodes and connections. Common topologies include bus, star, ring, and mesh, each impacting network performance, scalability, and fault tolerance. Understanding these arrangements is crucial for network design and troubleshooting.

Network Virtualization

Network virtualization abstracts network resources, creating a software-defined network environment. This allows for the creation of virtual networks, independent of physical hardware, enabling greater flexibility, scalability, and efficient resource utilization. It supports technologies like virtual machines and cloud computing.

NIC

A Network Interface Card (NIC) is a hardware component enabling a device’s connection to a network. It manages data transmission and reception, utilizing a MAC address for identification. NICs come in various form factors and support different network speeds and standards.

P

PoE

Power over Ethernet delivers electrical power alongside data transmission over standard Ethernet cabling. This simplifies network deployments by eliminating the need for separate power supplies for devices like IP phones, wireless access points, and security cameras, reducing cabling complexity and installation costs.

Port Forwarding

Port Forwarding is a network address translation (NAT) technique that redirects network traffic from a public IP address and port number to a specific private IP address and port number. This allows external devices to initiate connections to services hosted on a private network, such as web servers or game servers.

Port Security

Port Security is a Layer 2 switch feature that limits the number of MAC addresses that can be learned on a specific physical port. It can be configured to shut down the port or drop traffic if an unauthorized device is connected.

Power over Ethernet (PoE)

Power over Ethernet (PoE) delivers electrical power alongside data transmission via standard Ethernet cables. This eliminates the need for separate power supplies for devices like IP phones, security cameras, and wireless access points, simplifying installation and reducing cabling requirements.

Proxy Server

A proxy server acts as an intermediary between clients and destination servers. It enhances security by masking internal IP addresses, improves performance through caching frequently accessed content, and enables content filtering based on organizational policies. Proxies manage client requests and server responses.

S

SD-WAN

SD-WAN (Software-Defined Wide Area Network) is a virtualized WAN transport utilizing software to centrally manage and optimize network traffic. It abstracts network hardware from connectivity, enabling dynamic path selection based on application requirements and cost. SD-WAN improves performance and reduces operational expenses.

Secure Access Service Edge (SASE)

Secure Access Service Edge (SASE) is a cloud architecture model that converges wide area networking (SD-WAN) with comprehensive security functions, such as secure web gateways and cloud access security brokers. It delivers security and connectivity directly to the user at the network edge.

Secure File Transfer Protocol (SFTP)

Secure File Transfer Protocol (SFTP) is a network protocol that provides file access, transfer, and management over any reliable data stream. It leverages SSH to provide a secure, encrypted connection for transferring files between a client and server.

Secure Shell (SSH)

Secure Shell (SSH) is a cryptographic network protocol used for operating network services securely over an unsecured network. It provides a secure channel for remote command-line login and other network services, replacing insecure protocols like Telnet by encrypting all traffic.

Service Set Identifier (SSID)

A Service Set Identifier (SSID) is a unique case-sensitive alphanumeric string that identifies a specific wireless local area network (WLAN). It acts as the network name that users see and select when connecting their devices to a wireless access point.

Session Initiation Protocol (SIP)

Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, modifying, and terminating real-time sessions that involve video, voice, and messaging. It is the foundational protocol for Voice over IP (VoIP) communications, handling the setup of the call rather than the data transport.

Simple Network Management Protocol (SNMP)

Simple Network Management Protocol (SNMP) is an application-layer protocol used for exchanging management information between network devices and a network management system. It allows administrators to monitor device performance, track errors, and configure remote devices using a standardized management information base (MIB).

Site-to-Site VPN

A Site-to-Site VPN is a permanent encrypted connection between two separate networks, typically connecting a branch office to a central corporate headquarters. It uses a VPN gateway at each site to tunnel traffic securely over the public internet.

Software-Defined Networking (SDN)

Software-Defined Networking (SDN) is a network architecture approach that decouples the control plane from the data plane. This allows network administrators to manage network behavior centrally via software, increasing flexibility and automating the configuration of physical hardware.

Software-Defined Wide Area Network (SD-WAN)

Software-Defined Wide Area Network (SD-WAN) is a virtualized service that connects and coordinates WAN connections to offices. It uses a centralized control function to dynamically route traffic across the WAN using various transport services such as MPLS, LTE, and broadband internet.

Spanning Tree Protocol (STP)

Spanning Tree Protocol (STP) is a Layer 2 protocol preventing network loops in Ethernet networks. It dynamically blocks redundant paths to create a loop-free logical topology, ensuring stable data transmission and preventing broadcast storms. Multiple versions exist, each improving convergence times.

SSID

Service Set Identifier (SSID) is a 32-character alphanumeric identifier that uniquely names a wireless local area network (WLAN). It is broadcasted via beacon frames, allowing devices to discover available networks. While often used for identification, SSIDs do not provide inherent security and can be hidden, though this is not a security measure.

Subnet Mask

A subnet mask is a 32-bit number used to divide an IP address into network and host portions. It determines the network size and the maximum number of usable host addresses within that network. The mask identifies which bits represent the network and which represent the host.

Subnetting

Subnetting is the division of a larger IP network into smaller, logically separate subnetworks. This process improves network efficiency, enhances security, and simplifies network administration by reducing broadcast traffic and enabling more granular control over network resources.

Switch

A network switch is a Layer 2 device that connects devices within a network using MAC addresses. It learns MAC addresses and forwards data only to the intended destination port, improving network efficiency. Switches create collision domains and can support VLANs for network segmentation and enhanced security.

Syslog

Syslog is a standard for message logging that allows network devices to send event notifications and status messages to a central logging server. These logs are categorized by severity levels, ranging from emergency to debug, to help administrators troubleshoot issues.

T

TACACS+

Terminal Access Controller Access-Control System Plus (TACACS+) is a network protocol delivering AAA services, primarily for Cisco devices. It provides granular control over user access and network resources through authentication, authorization, and accounting functions.

TCP

Transmission Control Protocol is a connection-oriented protocol ensuring reliable data transmission. It establishes a connection using a three-way handshake, provides ordered delivery, and incorporates error checking mechanisms like checksums and acknowledgements to guarantee data integrity during network communication.

TCP/IP Model

The TCP/IP model is a suite of communication protocols used to interconnect network devices on the internet. Consisting of four layers – Network Access, Internet, Transport, and Application – it provides a practical, implementation-focused alternative to the more theoretical OSI model.

Telnet

Telnet is an older network protocol used to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. Because it transmits data in plaintext, it is considered insecure and is largely replaced by SSH.

Terminal Access Controller Access-Control System Plus (TACACS+)

Terminal Access Controller Access-Control System Plus (TACACS+) is a protocol used for AAA services, specifically designed for device administration. Unlike RADIUS, it separates authentication, authorization, and accounting functions and encrypts the entire packet payload for enhanced security.

Throughput

Throughput represents the actual rate of successful data delivery over a network connection, measured in bits per second (bps). It differs from bandwidth, which is the theoretical maximum capacity. Throughput is affected by factors like network congestion, overhead, and hardware limitations, resulting in a lower practical data transfer rate.

Time to Live (TTL)

Time to Live (TTL) is a value in an IP packet that prevents a packet from circulating indefinitely in a network loop. Each router that processes the packet decrements the TTL value by one; if the value reaches zero, the packet is discarded.

Traceroute (tracert)

Traceroute is a diagnostic tool used to map the path a packet takes from a source to a destination. It utilizes the Time-to-Live (TTL) field in IP headers to identify every single hop (router) along the network path.

Transmission Control Protocol (TCP)

Transmission Control Protocol (TCP) is a connection-oriented transport layer protocol that ensures reliable delivery of data packets. It utilizes a three-way handshake to establish connections and provides error checking and sequencing to guarantee that data arrives intact and in the correct order.

Troubleshooting Methodology

A troubleshooting methodology is a structured, systematic approach to identifying and resolving network problems. It typically involves problem definition, data collection, hypothesis development, testing, solution implementation, and documentation. Effective methodology minimizes downtime and ensures efficient issue resolution.

V

Virtual Extensible LAN (VXLAN)

Virtual Extensible LAN (VXLAN) is a Layer 2 overlay scheme on a Layer 3 network used to provide network virtualization. It encapsulates Ethernet frames in UDP packets, allowing for the creation of millions of virtual networks, overcoming the 4,096 VLAN ID limit.

Virtual LAN (VLAN)

A Virtual LAN (VLAN) is a logical grouping of network devices that allows network administrators to segment a physical network into multiple broadcast domains. This enhances security, simplifies network management, and improves network performance by reducing broadcast traffic.

Virtual Local Area Network (VLAN)

Virtual Local Area Network (VLAN) is a logical grouping of devices on one or more LANs that are configured to communicate as if they were attached to the same wire. This allows network administrators to segment traffic for security and performance.

Virtual Private Network (VPN)

A Virtual Private Network (VPN) creates an encrypted tunnel over a public network to provide secure, private access to a remote network. It ensures data confidentiality and integrity using tunneling protocols and encryption.

Virtual Router Redundancy Protocol (VRRP)

Virtual Router Redundancy Protocol (VRRP) is a standard protocol that eliminates the single point of failure for a default gateway by grouping multiple routers into a virtual redundancy group. It provides a single virtual IP address that hosts use as their gateway, ensuring connectivity if the primary router fails.

Virtualization

Virtualization creates abstracted, software-defined versions of physical IT resources—servers, storage, networks, and operating systems—allowing multiple virtual instances to run concurrently on a single physical host. This maximizes resource utilization, improves scalability, and reduces capital expenditure.

VLAN

A Virtual LAN (VLAN) is a logically segmented broadcast domain within a physical network, operating at Layer 2. VLANs enhance security, simplify network administration, and improve performance by isolating traffic. They are configured on switches to group ports, regardless of physical location, into distinct networks.

VLSM

Variable Length Subnet Masking (VLSM) optimizes IP address allocation by employing different subnet masks for varying network segment sizes. This technique avoids address wastage inherent in fixed-length subnetting, enabling efficient network design and resource utilization. It’s essential for complex network environments.

VoIP

Voice over Internet Protocol (VoIP) transmits voice communications over an IP network using packet switching. This technology converts analog voice signals into digital data packets for transmission, offering cost savings and integration with other IP-based services.

VPN

A Virtual Private Network (VPN) creates a secure, encrypted connection over a public network like the internet. It enables remote users to securely access private network resources as if directly connected. VPNs protect data confidentiality and integrity by tunneling traffic through an encrypted pathway, masking the user’s IP address.

W

WAN

A Wide Area Network extends network connectivity across large geographical distances, typically utilizing technologies like MPLS, SD-WAN, or dedicated circuits. WANs connect multiple LANs, enabling communication between geographically dispersed locations and remote users.

WEP

Wired Equivalent Privacy (WEP) is an outdated wireless security protocol utilizing the RC4 stream cipher. It was designed to provide confidentiality comparable to wired networks but contains critical flaws. WEP is easily compromised due to its short initialization vector (IV) and weak key scheduling algorithm, rendering it insecure.

Wi-Fi Protected Access 3 (WPA3)

Wi-Fi Protected Access 3 (WPA3) is the latest security certification for wireless networks, replacing WPA2 to provide stronger encryption and improved protection against brute-force attacks. It introduces Simultaneous Authentication of Equals (SAE) to replace the vulnerable Pre-Shared Key (PSK) handshake.

Wireless Access Point (WAP)

A Wireless Access Point (WAP) extends a wired network, enabling wireless devices to connect using radio waves. It functions as a bridge, translating wireless signals to wired signals and vice versa. WAPs broadcast a Service Set Identifier (SSID) to identify the network and manage wireless connections.

Wireless Encryption

Wireless encryption secures wireless communication by encoding data transmitted over the air, preventing unauthorized access and eavesdropping. Encryption protocols like WPA2 and WPA3 protect the confidentiality and integrity of wireless network traffic. It’s fundamental to wireless network security.

Wireless Standards (802.11 a/b/g/n/ac/ax)

The 802.11 family defines WLAN standards, each offering varying data rates, frequencies, and modulation techniques. These standards dictate how wireless devices communicate, with newer versions like 802.11ax (Wi-Fi 6) providing increased speed and efficiency through technologies like OFDMA and MU-MIMO.

Wireless Standards (802.11)

The 802.11 family defines standards for Wireless Local Area Networks (WLANs). Successive iterations (a/b/g/n/ac/ax/be) introduce improvements in speed, range, and security. These standards operate on different frequency bands (2.4 GHz, 5 GHz, 6 GHz) and utilize various modulation techniques.

WPA3

Wi-Fi Protected Access 3 (WPA3) is the latest wireless security standard, offering enhanced protection against brute-force attacks. It mandates Protected Management Frames (PMF) for increased robustness and introduces Simultaneous Authentication of Equals (SAE), replacing the WPA2 pre-shared key (PSK) exchange with a more secure handshake.