Background and History of Subnet Masks Subnet masks were officially introduced to the TCP/IP protocol stack through RFC 950 in 1985 as an innovative technology to solve the serious inefficiency problems of the early internet’s classful addressing system. In the early 1980s, the internet used the A, B, C class system. Class A was identified by the first byte (1-126) supporting approximately 16 million hosts, Class B by the second byte (128-191) supporting approximately 65,000 hosts, and Class C by the third byte (192-223) supporting 254 hosts. This rigid structure caused critical problems. Organizations needing 1,000 hosts had to be allocated Class B (65,534) as Class C (254) was insufficient, wasting over 64,000 IP addresses. Conversely, organizations needing only 300 hosts had to be allocated an entire Class C (254), offering no flexibility. Subnet masks emerged to solve this inefficiency by enabling division of one network into multiple small subnetworks (subnets), allowing arbitrary adjustment of boundaries between network and host portions to precisely allocate the required number of hosts, forming the foundation for CIDR (Classless Inter-Domain Routing) introduction in 1993 and becoming a core concept of modern internet address management. ...

Background and History of CIDR CIDR (Classless Inter-Domain Routing) was officially introduced by the IETF in 1993 through RFC 1517, RFC 1518, and RFC 1519 to overcome the serious limitations of the existing class-based IP address allocation method, and later revised as RFC 2050 in 1998 to become the internet routing standard. From the late 1980s, as the internet grew rapidly, the existing classful addressing system faced two serious problems. First, Class C networks (254 hosts) were too small and Class B networks (65,534 hosts) were too large, not matching actual needs and wasting large amounts of IP addresses. Second, internet routing tables exploded, causing overload on router memory and processing performance. CIDR solved these problems by completely removing the class concept and introducing Variable Length Subnet Mask (VLSM) to allow precise adjustment of network sizes as needed, and enabled dramatic reduction in routing table size through route aggregation or supernetting techniques that consolidate multiple small networks into a single routing entry. ...

What is Classful Addressing Classful Addressing is an IP address allocation method officially introduced in 1981 through the IETF’s RFC 791 document alongside the IPv4 protocol. It was designed to efficiently distribute address space and minimize routing tables in the early Internet network. The system divides network sizes into 5 classes (A, B, C, D, E) based on the bit pattern of the first octet (8 bits) of the IP address, providing different sizes of network address space for each class. ...

What is RAID? RAID (Redundant Array of Independent Disks) is a data storage virtualization technology that combines multiple physical hard disks into a single logical unit to improve data reliability or enhance input/output performance. It was first proposed in the 1988 paper “A Case for Redundant Arrays of Inexpensive Disks” by David Patterson, Garth A. Gibson, and Randy Katz at the University of California, Berkeley. At the time, it stood for “Inexpensive Disks,” but the meaning later changed to “Independent Disks.” The technology originated from the goal of achieving both cost efficiency and reliability by combining multiple small disks instead of using a single large-capacity disk. ...

Docker Compose is a tool for defining and running multi-container Docker applications that uses YAML files to configure application services, allows you to create and start all services with a single command, ensures consistency between development and production environments, and simplifies the management of complex multi-container architectures. Docker Compose Overview What is Docker Compose? Docker Compose is a tool for defining, running, and managing applications composed of multiple containers. It allows you to declaratively define services, networks, and volumes in a docker-compose.yml file and manage the entire application stack with a single command. ...

Docker image optimization is a core technology that directly impacts build time reduction, deployment speed improvement, storage cost savings, and security vulnerability reduction for container-based applications. By applying techniques such as appropriate base image selection, multi-stage builds, and layer optimization, you can reduce image size by 10x or more, which also significantly affects CI/CD pipeline efficiency and cloud infrastructure costs. Understanding Docker Image Size Problems Why is Image Size Important? ...

Docker is a platform for developing, deploying, and running container-based applications. It uses Linux kernel namespaces and cgroups to run applications in isolated environments. This guide explains the step-by-step process of installing Docker and running your first container on Ubuntu Linux. Docker Installation Requirements Docker Installation Requirements Docker Engine runs on 64-bit Linux systems and requires kernel version 3.10 or higher. For Ubuntu, versions 20.04 LTS, 22.04 LTS, and 24.04 LTS are officially supported. ...

Container technology is a revolutionary innovation that has fundamentally transformed modern software development and deployment. Docker is the key platform that popularized this container technology, and since its introduction in 2013, it has become the standard for microservices architecture, CI/CD pipelines, and cloud-native computing. History of Container Technology and the Birth of Docker What is a Container? A container is a lightweight virtualization technology that packages an application along with all its dependencies (libraries, configuration files, binaries, etc.) into a single standardized package, enabling identical execution anywhere. ...

Packaging React applications as Docker containers maintains consistency between development and production environments, facilitates integration with CI/CD pipelines, enables using the same image across various deployment environments (Kubernetes, AWS ECS, Azure Container Instances, etc.) to standardize deployment processes, and allows creating optimized production images through multi-stage builds and nginx-based static file serving. Understanding React Application Containerization Why Containerize React Apps? React is a client-side JavaScript application that, after building, is bundled into static files (HTML, CSS, JavaScript) and served through a web server. Using Docker containers ensures build environment consistency, enables deployment automation, and simplifies environment-specific configuration management. ...

Docker image layers are the fundamental building blocks of Docker images. Each layer captures filesystem changes and stacks as a read-only tier on top of previous layers. These layers are unified into a single filesystem through the Union File System and provided to containers. Understanding the layer structure is essential for efficient image building and storage optimization. Docker Image Layer Overview What is a Docker Image Layer? A Docker image layer is a filesystem snapshot generated by each instruction in a Dockerfile. Like Git commits, it stores only the changes from the previous state, maximizing space efficiency. ...