# Certbot: Detail: DNS problem: NXDOMAIN looking up A for www.example.com - check that a DNS record exists for this domain

**Code:** `DNS problem: NXDOMAIN looking up A` · **Category:** SSL / TLS · **Seen on:** SSL, Linux

Let's Encrypt could not resolve the domain you asked a certificate for; no A/AAAA record exists.

## Meaning

Every name in `-d` must resolve publicly to your server for HTTP-01 validation. Add the missing record, or remove that name from the request. Wait for DNS propagation and verify with `dig`. Also check for AAAA records pointing to an IPv6 address where the server isn't listening.

## Common causes

- No DNS record for the requested subdomain (often `www`)
- Domain not delegated or DNS not yet propagated
- Typo in the domain
- AAAA record pointing to a wrong IPv6 address
- Using the domain before registering/pointing it

## Quick fix

1. Create A/AAAA (or CNAME) records for each name
2. Verify: `dig +short A www.example.com`
3. Remove names that don't need a certificate

## Detailed fix by platform

### Linux

1. `dig +short A www.example.com; dig +short AAAA www.example.com`

## How to diagnose

1. **Record** — Exists for each -d?
2. **Propagation** — Resolved publicly?
3. **IPv6** — AAAA correct?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/ssl/certbot-dns-nxdomain-looking-up-a)