Tempo de Vida (TTL: Time to Live)
Contador numérico ou duração temporal que determina por quanto tempo um pacote de dados ou registro DNS permanece válido antes de ser descartado.
Entity Relationships (GEO Conceptual Hierarchy)
Taxonomy ModelTechnical Explanation & Operational Mechanics
No DNS (RFC 1035), o TTL define o número de segundos que os resolvedores recursivos podem manter um registro em cache. Em redes IP, limita o número de saltos para evitar loops infinitos de roteamento.
Technical Example & Practical Implementation
Configuração de TTL para migrações dinâmicas e balanceamento de carga.
; BIND Zone File Entry:
; Name TTL Class Type Target
api.example.com. 300 IN A 198.51.100.42
; Caching Resolver Timeline:
; Time = 0s: Resolver queries authoritative server, receives IP and TTL 300.
; Time = 100s: User 2 asks resolver -> served instantly from cache (TTL remaining: 200s).
; Time = 300s: Cache TTL hits 0s. Record is purged (expired).
; Time = 301s: User 3 asks resolver -> resolver must query authoritative server again.Related Topic Ecosystem & Next Steps
Artigos Técnicos Relacionados
What Is the Domain Name System (DNS)?
Direct explanation of hierarchical domain resolution from root servers to zone files.
DNS vs DNS-over-HTTPS (DoH): Privacy & Security
Traditional UDP port 53 lookups compared to encrypted TLS-encapsulated DoH queries.
Troubleshooting: DNS Returns NXDOMAIN Error
Diagnose missing records, propagation lag, and nameserver delegation failures.
Laboratórios Práticos de Diagnóstico
Especificações e Referências para Desenvolvedores
Continuar Aprendendo
DNS Resolution & Propagation Lab
Trace authoritative resolution from the root servers down to the zone file in the visual DNS workbench.