DNS Troubleshooting FAQ

This article provides guidance to troubleshoot common concerns about Cloudflare DNS.


Why do I have a dc-######### subdomain?

The dc-##### subdomain is added to overcome a conflict created when your MX record resolves to a domain configured to proxy to Cloudflare.

Do not orange-cloud DNS records used to receive mail: Cloudflare does not proxy mail traffic by default.

Therefore, Cloudflare will create a dc-##### DNS record that resolves to the origin IP address. The dc-##### record ensures that mail traffic isn’t proxied (it directly resolves to your origin IP) while the Cloudflare proxy works for all other traffic.

For example, before using Cloudflare, suppose your DNS records for mail are as follows:

example.com MX example.com
example.com A 192.0.2.1

After using Cloudflare and proxying the A record, CloudFlare will provide DNS responses with a Cloudflare IP (203.0.113.1 in the example below):

example.com MX example.com
example.com A 203.0.113.1

Since proxying mail traffic to Cloudflare would break your mail services, Cloudflare detects this situation and creates a dc-##### record:

example.com MX dc-1234abcd.example.com
dc-1234abcd.example.com A 192.0.2.1
example.com A 203.0.113.1

Removing the dc-###### record is only possible via one of these methods:

  • If no mail is received for the domain, delete the MX record.
  • If mail is received for the domain, update the MX record to resolve to a separate A record for a mail subdomain that isn’t proxied by Cloudflare:
example.com MX mail.example.com
mail.example.com A 192.0.2.1
example.com A 203.0.113.1
If your mail server resides on the same IP as your web server, your MX record will expose your origin IP address.

Why are DNS queries returning incorrect results?

Third-party tools can sometimes fail to return correct DNS results if a recursive DNS cache fails to refresh. In this circumstance, purge your public DNS cache via these methods:


No A, AAAA or CNAME record found?

No A, AAAA or CNAME record found means the Cloudflare DNS app lacks proper records for DNS resolution.

Add the missing DNS records to your domain.

Sites generally have at least an A record that points to the origin server IP address, typically for the www subdomain and the root domain.

Why have I received an email: Your Name Servers have Changed?

For domains where Cloudflare hosts the DNS, Cloudflare continuously checks whether the domain uses Cloudflare’s nameservers for DNS resolution. If Cloudflare's nameservers are not used, the domain status is updated from Active to Moved in the Cloudflare Overview app and an email is sent to the customer.

Steps to resolve the issue require updating the DNS at your domain registrar to utilize the Cloudflare nameservers:

  1. Follow the steps 2 and 3 within our domain troubleshooting article.
  2. Click Re-check Now in the Cloudflare UI Overview app.
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