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Sistema de nomes de domínio

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O Domain Name[1] System (DNS) is a vital part of the internet[2]’s infrastructure. It works as a translator between human-friendly hostnames and numerical IP addresses. This system helps users access websites and online services swiftly and efficiently. The DNS has been in use since the ARPANET era, where it began as a simple mapping system. Over time, it has developed into a complex hierarchical structure that is crucial for cloud services and content delivery networks. The DNS uses protocols like UDP and TCP to provide reliable, secure, and private connections. It also holds various types of records, such as SOA, A, AAAA, MX, NS, PTR, and CNAME, which are traditionally stored in a zone file. These records are important for the operation of distributed Internet services. The DNS helps users get faster responses by assigning proximal servers. Its structure is reflective of administrative responsibility on the internet, with zones of autonomy assigned to managers for each subdomain.

Definições de termos
1. Nome do domínio ( Domain Name ) A domain name is a text-based label that identifies internet resources such as computers and services. It serves as an indicator of ownership or control over a resource and provides an easily recognizable name for these resources. In structure, a domain name is made up of concatenated labels separated by dots, arranged in a descending hierarchy from right to left. Each label can contain 1 to 63 octets and the overall domain name should not exceed 253 ASCII characters. The Domain Name System (DNS) translates these domain names into IP addresses, helping to distribute web traffic across different servers. Domain names are organized into a tree structure, with Top-Level Domains (TLDs) such as .com, .org, .net at the highest level. The Internet Corporation for Assigned Names and Numbers (ICANN) oversees the allocation of TLDs and accredits domain registrars. Domain names can also be internationalized, with many registries adopting the Internationalized domain name (IDNA) system approved by ICANN. The domain name industry is subject to cyber threats like spoofing, but measures are in place for protection.
2. internet. A Internet é um sistema global de redes informáticas interligadas que utilizam protocolos de comunicação normalizados, principalmente o TCP/IP, para ligar dispositivos em todo o mundo. Com origem no termo "internetted" utilizado em 1849, o termo "Internet" foi mais tarde utilizado pelo Departamento de Guerra dos EUA em 1945. O seu desenvolvimento começou com cientistas informáticos que criaram sistemas de partilha de tempo na década de 1960 e progrediu com a criação da ARPANET em 1969. A Internet é autónoma, sem uma autoridade central, e os seus principais espaços de nomes são administrados pela Internet Corporation for Assigned Names and Numbers (ICANN). Transformou significativamente os meios de comunicação tradicionais e tem crescido exponencialmente ao longo dos anos, com os utilizadores da Internet a aumentarem anualmente de 20% para 50%. Em 2019, mais de metade da população mundial utilizou a Internet. O conjunto de protocolos da Internet, que inclui o TCP/IP e quatro camadas conceptuais, orienta os pacotes da Internet para os seus destinos. Serviços essenciais como o correio eletrónico e a telefonia via Internet funcionam na Internet. A World Wide Web, uma coleção global de documentos interligados, é uma componente essencial da Internet.

O Sistema de nomes de domínio (DNS) is a hierarchical and distributed naming system for computadores, services, and other resources in the Internet or other Protocolo Internet (IP) networks. It associates various information with domain names (identification strings) assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. The Domain Name System has been an essential component of the functionality of the Internet since 1985.

The Domain Name System delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain. Network administrators may delegate authority over subdomains of their allocated name space to other name servers. This mechanism provides distributed and fault-tolerant service and was designed to avoid a single large central database. In addition, the DNS specifies the technical functionality of the database service that is at its core. It defines the DNS protocol, a detailed specification of the data structures and data communication exchanges used in the DNS, as part of the Conjunto de protocolos Internet.

The Internet maintains two principal namespaces, the domain name hierarchy and the IP address spaces. The Domain Name System maintains the domain name hierarchy and provides translation services between it and the address spaces. Internet name servers and a communication protocol implement the Domain Name System. A DNS name server is a server that stores the DNS records for a domain; a DNS name server responds with answers to queries against its database.

The most common types of records stored in the DNS database are for start of authority (SOA), IP addresses (A e AAAA), SMTP mail exchangers (MX), name servers (NS), pointers for reverse DNS lookups (PTR), and domain name aliases (CNAME). Although not intended to be a general purpose database, DNS has been expanded over time to store records for other types of data for either automatic lookups, such as DNSSEC records, or for human queries such as responsible person (RP) records. As a general purpose database, the DNS has also been used in combating unsolicited email (spam) by storing a real-time blackhole list (RBL). The DNS database is traditionally stored in a structured text file, the zone file, but other database systems are common.

The Domain Name System originally used the User Datagram Protocol (UDP) as transport over IP. Reliability, security, and privacy concerns spawned the use of the Protocolo de Controlo de Transmissão (TCP) as well as numerous other protocol developments.

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