Domain Name System
DNS supplies data about names, such as a web server’s address. Name resolution, the server connection and application behaviour are separate steps.
What does DNS mean?
The Domain Name System (DNS) is a distributed system for data associated with domain names. This includes addresses and other record types. The IETF describes resolvers as programs that query name servers for such information. A resolver may use a suitable stored answer or query other servers.
Example: finding the portal’s address
In the fictional example, an application wants to reach portal.studio.example. It needs a suitable address for an IPv4 connection. DNS resolution provides that mapping; the connection, TLS where applicable and the actual application request follow. The name is a placeholder, not a publicly operated portal.
When the DNS mapping changes, stored answers may still be in use. The TTL (Time to Live) limits their normal reuse from cache. A change therefore does not mean an immediate switch visible everywhere.
A correct DNS answer does not prove that the web server is reachable or login works. When investigating a failure, the team should distinguish which step is affected.
Sources
Related terms
- DomainA domain is a named part of the DNS namespace. The name does not create a website; hosting, email and the application still need to be connected.
- A recordAn A record maps a DNS name to an IPv4 address. It does not configure the website or define HTTPS, paths or an HTTP redirect.
- DNS zoneA DNS zone is an administrative unit for DNS data. Its boundaries follow delegation; not every subdomain automatically becomes a separate zone.
- Return-PathReturn-Path records the SMTP reverse path in a header. It explains the technical route for error reports, not a person’s identity.
- Envelope-FromEnvelope-From identifies the SMTP sender for transport and error feedback. It must be distinguished from the visible sender address.
- DMARC aggregate reportA DMARC aggregate report summarises a reporting mail system’s domain checks over a period. It helps examine sending sources and misconfigurations.
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