Certified - CompTIA IT Fundamentals+

In this final glossary episode, we’ll explore the remaining acronyms from O to Z. These terms include essential technologies in email, encryption, protocols, system security, cloud computing, and virtualization.
By the end of this episode, you’ll have reviewed more than 140 of the most common acronyms tested on the ITF Plus exam. These short-form terms are easy to confuse, so this final batch is just as important as the rest.
Service-Level Agreement, or S L A, is a contract that defines the expected level of service between a provider and a customer. It may include uptime guarantees, response times, and support terms. S L As are common in cloud and managed service agreements.
SUSE Linux Enterprise Server, or S L E S, is a commercial Linux distribution built for servers and enterprise environments. It is maintained by S U S E and focuses on reliability, scalability, and support. S L E S is used in many corporate and government infrastructures.
Service-Level Indicator, or S L I, is a specific metric used to measure the performance of a service, such as uptime or response time. It provides the actual value that’s tracked for monitoring service quality. S L Is are often used to evaluate whether a service meets its targets.
Service-Level Objective, or S L O, defines a target value for a service-level indicator. For example, an S L O might state that uptime should remain above ninety-nine point nine percent. S L Os help organizations set expectations and measure compliance.
Server Message Block, or S M B, is a protocol used for file sharing over a network. It allows Windows computers and other systems to access shared files and printers. S M B is often used alongside C I F S in local network environments.
Simple Mail Transfer Protocol, or S M T P, is used to send email messages between servers. It does not handle receiving or storing emails. S M T P works in combination with other protocols like I M A P and P O P 3.
Source Network Address Translation, or S N A T, modifies the source I P address of packets as they leave a network. This is commonly done to enable internal devices to share a public I P. S N A T is used in firewalls and routers to manage outbound traffic.
Simple Network Management Protocol, or S N M P, is used to monitor and manage network devices such as routers, switches, and servers. It collects information about device status and performance. S N M P relies on M I B files to define data formats.
Single Root Input Output Virtualization, or S R dash I O V, allows a single physical network interface to appear as multiple virtual interfaces. It improves performance and isolation in virtualized environments. S R dash I O V is commonly used in data centers and cloud platforms.
Solid-State Drive, or S S D, is a storage device that uses flash memory instead of spinning disks. S S Ds are faster, more durable, and more energy-efficient than traditional hard drives. They are now common in laptops, desktops, and servers.
Secure Shell, or S S H, is a protocol used for secure remote access to computers and servers. It encrypts communication to prevent eavesdropping and tampering. S S H is widely used in managing Linux and Unix systems.
Secure Shell Daemon, or S S H D, is the background process that handles incoming S S H connections. It listens for requests and establishes encrypted sessions. Without S S H D, a system cannot accept remote S S H logins.
Secure Sockets Layer, or S S L, is a now-deprecated protocol used to encrypt communication over the internet. It has been replaced by Transport Layer Security, or T L S. You should recognize S S L as a legacy encryption protocol.
Single Sign-On, or S S O, allows users to access multiple systems or services with one login credential. It simplifies user experience and reduces password fatigue. S S O is often implemented in enterprise and cloud environments.
System Security Services Daemon, or S S S D, is a Linux service that manages access to remote directories and authentication sources. It provides caching and failover for directory services. S S S D improves reliability when integrating with L D A P or Active Directory.
Secure Sockets Services Daemon, or S S S D, is sometimes used interchangeably with the System Security Services Daemon. Both refer to services that manage identity, access, and authentication. While you may see alternate phrasing, the acronym usage is usually consistent in Linux security.
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Transmission Control Protocol, or T C P, is a reliable, connection-oriented protocol used for sending data across networks. It ensures packets arrive in order and without loss. T C P is used by applications like web browsers, email, and file transfer tools.
Trivial File Transfer Protocol, or T F T P, is a simple, lightweight file transfer protocol. It lacks authentication and is often used for tasks like booting systems or transferring firmware. T F T P trades security and features for speed and simplicity.
Transport Layer Security, or T L S, is the modern protocol used to encrypt internet traffic. It replaces S S L and secures web browsers, email, and voice communications. T L S ensures confidentiality and integrity of data in transit.
Time-based One-Time Password, or T O T P, is a temporary code used for two-factor authentication. The password changes every thirty seconds and is generated from a shared secret and the current time. T O T P is often used with authentication apps.
Time to Live, or T T L, is a value in a data packet that limits how long the packet can exist on a network. Each router it passes through reduces the T T L by one. When T T L reaches zero, the packet is discarded to prevent loops.
User Datagram Protocol, or U D P, is a connectionless protocol used for fast, lightweight data transmission. Unlike T C P, it does not guarantee delivery or order. U D P is ideal for streaming media and real-time communication.
Unified Extensible Firmware Interface, or U E F I, is the modern replacement for B I O S firmware in computers. It provides a graphical interface and supports larger disks and faster booting. U E F I is required for systems using G P T partitioning.
Uncomplicated Firewall, or U F W, is a user-friendly firewall configuration tool for Linux. It simplifies managing I P tables rules and allows quick setup of basic security policies. U F W is commonly used on Ubuntu systems.
Unique Identifier, or U I D, is a numeric value assigned to a user in Unix-like systems. It determines access permissions for files and processes. The root user typically has a U I D of zero.
Universal Serial Bus, or USB, is a common interface for connecting external devices to a computer. It supports data transfer, power delivery, and device communication. USB has largely replaced older ports like serial and parallel connectors.
Universally Unique Identifier, or U U I D, is a 128-bit value used to uniquely identify information in computer systems. It’s often used in software development, databases, and device tracking. U U I Ds are designed to be globally unique across time and space.
V I Improved, or V I M, is a text editor used in Unix and Linux environments. It is an enhanced version of the original V I editor. V I M supports powerful keyboard-based editing and customization.
Virtual Machine, or VM, is a software-based emulation of a physical computer. It runs an operating system and applications just like a physical system. VMs are managed by hypervisors such as K VM or VM Ware.
Wide Area Network, or W A N, is a network that connects computers across large geographical distances. The internet is the largest example of a W A N. These networks often rely on leased lines or public infrastructure.
Extensible Markup Language, or X M L, is a flexible text format used to store and transport structured data. It uses custom tags to describe data elements. X M L is used in configuration files, web services, and data interchange formats.
Y A M L Ain’t Markup Language, or Y A M L, is a human-readable data serialization format. It is used for configuration files and data input in tools like Ansible and Kubernetes. Y A M L emphasizes clarity and simplicity over strict syntax.
This completes Episode 10 and our three-part glossary series for the ITF Plus PrepCast. You’ve now reviewed all major acronyms from A to Z, strengthening your exam readiness. In the next episode, we return to core concepts with hands-on instruction in key exam domains.