---
title: "DNS (Domain Name System) — monitoring glossary"
description: "The Domain Name System (DNS) is the distributed database that translates human-readable domain names like lemwatch.com into the IP addresses computers use to…"
canonical: "https://lemwatch.com/glossary/dns"
source: "https://lemwatch.com"
---

# DNS (Domain Name System)

> The Domain Name System (DNS) is the distributed database that translates human-readable domain names like lemwatch.com into the IP addresses computers use to route traffic. It is the address book of the internet.

## Definition

 DNS resolution involves multiple steps: the recursive resolver queries root servers, then top-level-domain servers (.com), then authoritative servers for the domain, then caches the result for the TTL specified by the record. Common record types include A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail server), TXT (arbitrary text, used for SPF/DKIM/DMARC verification), and NS (authoritative servers).

 DNS changes propagate based on TTL — a 24-hour TTL means it can take a full day for changes to fully reach every resolver worldwide.

## Why it matters

 An accidental DNS change can take an entire site offline. Monitoring DNS records for unauthorised modifications — and alerting on changes to A, MX, NS, and CNAME records — is essential for any business-critical domain.

 See it in the product: [DNS monitoring](https://lemwatch.com/features).



## Lemwatch at a glance

- What it is: website monitoring that checks uptime, page changes, SEO, security, SSL and speed in one tool.
- Free plan: 10 sites, no time limit, all check types.
- Pro: $19/mo, 50 sites, public API and webhooks.
- Agency: $59/mo, 150 sites, white-label status pages.
- Source: https://lemwatch.com/pricing (facts verified from the product's own plan limits).



## Related

- [Monitoring glossary](https://lemwatch.com/glossary)
- [Domain Expiry](https://lemwatch.com/glossary/domain-expiry)
- [SPF](https://lemwatch.com/glossary/spf)
- [DMARC](https://lemwatch.com/glossary/dmarc)
- [RDAP](https://lemwatch.com/glossary/rdap)
- [All monitoring checks](https://lemwatch.com/features)