---
title: "A records explained"
description: "What an A record does, how TTL and multiple A records behave, and how to add one in DNSense without breaking a live site."
canonical_url: "https://dnsense.io/learn/a-records-explained"
---

> Index of every page on this site: [llms.txt](https://dnsense.io/llms.txt)

An A record is the oldest and most common DNS record. It answers one question: which IPv4 address belongs to this name? Everything else on a website, from the certificate to the CDN, comes after that answer.

## How it works

A browser asks a resolver for `www.example.com`. The resolver asks the nameservers of the zone and gets an A record back, `203.0.113.10` for example. The browser connects to that address.

![A lookup for www.example.com returning the A record 203.0.113.10](guide-records-a.webp)

## What is in the record

- **Name.** `www`, `api`, or empty for the bare domain, called the apex or root.
- **Content.** One IPv4 address in dotted form. Not a hostname, not a URL.
- **TTL.** How long resolvers may cache the answer, in seconds. 3600 (one hour) is a sane default. 300 suits a change you expect to redo soon.

## More than one A record

Give a name several A records and resolvers return all of them, usually in rotating order. That is round-robin DNS: cheap load spreading, but it does not notice a dead server. If one of the addresses stops answering, some visitors still get sent there until you remove the record. For real failover you want a load balancer or health checks at the provider.

## Changing an A record safely

The old answer lives in caches for as long as the TTL says. So lower the TTL a day before a migration, change the address, then raise the TTL again. Changing the address first and the TTL second does nothing for the visitors who already cached it.

## Adding one in DNSense

Open the zone and click **Create record**. The type is A by default. Enter the name (empty for the apex), paste the IPv4 address and pick a TTL. DNSense refuses anything that is not a valid IPv4 address before it reaches your provider. **Add to queue** collects several records so you can send them together.

![The New record dialog with an A record for blog.example.com](app-records-a-form.webp)

Filter the table on type A afterwards to check the result.

![The zone filtered on A records](app-records-a-list.webp)

Every change lands in Time machine, so a wrong address is one click from undone. Mind the provider limits: Porkbun and GoDaddy have a minimum TTL of 600 seconds, and Openprovider only keeps a fixed list of TTL values.

## A or AAAA?

An A record only covers IPv4. If your server also has an IPv6 address, add an AAAA record next to it. That is the next article in this series.

## Sitemap

See the full [sitemap](https://dnsense.io/sitemap.md) for all pages.