---
title: "DNS (Domain Name System) — Definition | FourSight Glossary"
url: https://foursight.cloud/glossary/dns
description: "The internet's address book — translates human-readable domain names like foursight.cloud into IP addresses that computers route traffic to."
lang: en
---

Back to glossary: https://foursight.cloud/glossary

Web & Networking

# DNS (Domain Name System)

The internet's address book — translates human-readable domain names like foursight.cloud into IP addresses that computers route traffic to.

Source

- IETF — RFC 1035 — Domain Names — Implementation and Specification (https://datatracker.ietf.org/doc/html/rfc1035)

Related guide: DNS Monitoring Guide: https://foursight.cloud/guides/dns-monitoring-guide

## Related terms

HTTP Status Codes (2xx / 4xx / 5xx)

Three-digit response codes returned by HTTP servers.
https://foursight.cloud/glossary/http-status-codes

Timeout

The maximum time a client waits for a response before giving up.
https://foursight.cloud/glossary/timeout

A Record

A DNS record that maps a hostname to an IPv4 address (e.g.
https://foursight.cloud/glossary/a-record

AAAA Record

Maps a hostname to an IPv6 address.
https://foursight.cloud/glossary/aaaa-record

CNAME Record

An alias DNS record that points one hostname to another (e.g.
https://foursight.cloud/glossary/cname-record

MX Record

Identifies the mail servers responsible for accepting email for a domain.
https://foursight.cloud/glossary/mx-record

## Start monitoring free — HTTP + Ping checks, 4 regions, no card

The Free plan includes 10 monitors with HTTP and Ping checks from all 4 probe regions, 5 minute intervals, email alerts, and 1 status page — $0, no credit card, commercial use allowed. All 8 monitor types unlock on Growth ($40/mo).

- HTTP + Ping checks
- 4 probe regions on every plan
- No credit card

Start monitoring free: https://foursight.cloud/auth?signup=true

## Structured data

```json
[
  {
    "@context": "https://schema.org",
    "@type": "DefinedTerm",
    "@id": "https://foursight.cloud/glossary/dns",
    "name": "DNS (Domain Name System)",
    "description": "The internet's address book — translates human-readable domain names like foursight.cloud into IP addresses that computers route traffic to.",
    "url": "https://foursight.cloud/glossary/dns",
    "termCode": "dns",
    "inDefinedTermSet": {
      "@type": "DefinedTermSet",
      "name": "FourSight Monitoring & Reliability Glossary",
      "url": "https://foursight.cloud/glossary"
    },
    "sameAs": [
      "https://datatracker.ietf.org/doc/html/rfc1035"
    ]
  },
  {
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    "itemListElement": [
      {
        "@type": "ListItem",
        "position": 1,
        "name": "Glossary",
        "item": "https://foursight.cloud/glossary"
      },
      {
        "@type": "ListItem",
        "position": 2,
        "name": "DNS (Domain Name System)",
        "item": "https://foursight.cloud/glossary/dns"
      }
    ]
  }
]
```