Protocol

Background and History of NAT NAT (Network Address Translation) is a core technology that translates between private and public IP addresses in network communications. It emerged in the mid-1990s as a response to IPv4 address depletion. The first standard appeared in RFC 1631 in 1994, and RFC 2663 revised the concept into its current form in 1999. The early internet assumed that every device would have a unique public IP address, but rapid growth from the late 1980s quickly exhausted the 32-bit IPv4 address space of about 4.3 billion addresses. Although NAT began as a short-term workaround, it became a foundational part of global network infrastructure. It is now used everywhere from home routers to large corporate networks, cloud infrastructure, and mobile communication networks. Even as IPv6 adoption continues, NAT still plays an important role in legacy system support and security. ...

What is NDP NDP (Neighbor Discovery Protocol) is a core IPv6 protocol defined in RFC 4861. It combines the roles of several IPv4-era mechanisms such as ARP (Address Resolution Protocol), ICMP Router Discovery, and ICMP Redirect into a single protocol, making IPv6 network management more consistent and efficient. Built on ICMPv6 (Internet Control Message Protocol version 6), it handles functions such as neighbor discovery, router discovery, automatic address configuration, duplicate address detection, and path optimization. ...

What is ARP ARP (Address Resolution Protocol) is a network protocol defined in RFC 826 by the IETF in 1982. In TCP/IP networks, it dynamically discovers the MAC address (physical address) associated with a given IP address. It sits at the boundary between Layer 2 (Data Link Layer) and Layer 3 (Network Layer) of the OSI 7-layer model and maps logical addresses (IP) to physical addresses (MAC). In network communication, actual data transmission between devices relies on MAC addresses. The upper layer (Network Layer) works with IP addresses, but the lower layer (Data Link Layer) needs the destination’s MAC address to send packets. ARP performs this IP-to-MAC conversion. It broadcasts a query across the network, and only the device that owns the target IP responds. Because of this, ARP is an essential protocol in most local network environments, including Ethernet networks. ...

Overview When accessing websites on the internet, we use domain names instead of IP addresses. DNS (Domain Name System) is the system that translates these domain names into actual server IP addresses. Often compared to the internet’s phone book, DNS was designed by Paul Mockapetris in 1983 and has since become a core internet infrastructure. It processes billions of DNS queries daily, enabling users to access web services using intuitive domain names like www.example.com without memorizing complex IP addresses like 192.168.0.1 or 2001:4860:4860::8888. ...

Overview Network communication involves many interacting processes, and making sense of them requires a standardized reference model. The OSI (Open Systems Interconnection) 7-layer model is a network communication standard published by the International Organization for Standardization (ISO) in 1984. It divides communication between different systems into seven layers, defining how each layer operates independently while cooperating with others to transmit data. This model serves as a fundamental conceptual framework for network engineers and software developers to understand communication processes and diagnose problems. ...

HTTP status codes are standardized three-digit response codes that a server returns to indicate the result of processing a client’s request. These codes play a crucial role in HTTP-based communication for web browsers, API clients, and search engines by showing whether a request succeeds, requires redirection, or fails with a client-side or server-side error. In RESTful API design, choosing the right status codes has a major impact on API clarity and developer experience. ...

HTTP (HyperText Transfer Protocol) methods define how clients and servers communicate on the web. HTTP/1.1 (RFC 7231) defines 9 standard methods: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS, CONNECT, and TRACE. Each method has important properties such as safety and idempotency, which shape caching, retry behavior, RESTful API design, and web application development. History and Evolution of HTTP Methods What is HTTP (HyperText Transfer Protocol)? An application layer protocol for transferring hypertext documents between clients and servers on the web. It operates on a request-response model where the method used in each request defines the semantics of the operation to be performed. ...