DNS problem: NXDOMAIN looking up A SSL / TLS Origin: Network OSI layer 7 · Application Last updated 4 Nov 2026

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

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

Exact message you may see DNS problem: NXDOMAIN looking up A forDNS problem: NXDOMAIN looking up A for www.example.com - check that a DNS record exists for this domainDNS problem: SERVFAIL looking up CAADNS problem: looking up A for example.com: DNSSEC: DNSKEY MissingDetail: DNS problem: NXDOMAIN
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Seen on: SSL Linux

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?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Network. Errors that are often confused with or caused by this one (click to open):

1000 — Cloudflare Error 1000: DNS points to prohibited IP (Cloudflare)10001001 — Cloudflare Error 1001: DNS resolution error (Cloudflare)10011002 — Cloudflare Error 1002: DNS points to Prohibited IP / Restricted (Cloudflare)10021003 — Cloudflare Error 1003: Direct IP access not allowed (Cloudflare)10031004 — Cloudflare Error 1004: Host Not Configured to Serve Web Traffic (Cloudflare)10041014 — Cloudflare Error 1014: CNAME Cross-User Banned (Cloudflare)10141016 — Cloudflare Error 1016: Origin DNS error (Cloudflare)10161018 — Cloudflare Error 1018: Could not find host (Cloudflare)1018DNS probl…

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