Hostname verification

Cloudflare verifies ownership of each new hostname before traffic is allowed to proxy. There are four methods to verify ownership: TXT record, HTTP token, CNAME, or Apex.

​CNAME

​Full setup

Cloudflare iterates over the CNAME chain starting from the hostname. The value of the last CNAME must contain the domain that owns the custom hostname record. For example, if the domain owning the custom hostname record is saasprovider.com, then the CNAME looks similar to app.example.com CNAME proxy-fallback.saasprovider.com

​Partial setup

​If using Cloudflare for a partial setup

1. Add a CNAME record to Cloudflare DNS for your domain:

   app.example.com CNAME proxy-fallback.saasprovider.com

2. Add a CNAME record to your authoritative DNS to point to the fallback origin:

   proxy-fallback.saasprovider.com CNAME proxy-fallback.saasprovider.com.cdn.cloudflare.net

​If using another DNS provider

1. Log into your authoritative DNS provider.

2. Add a CNAME record to point to the fallback origin owned by the SaaS provider.

   app.example.com CNAME proxy-fallback.saasprovider.com

​Apex verification

For verification, the account that owns the custom hostname must also own all A and AAAA records for the apex. To verify ownership, the IP returned for the hostname must reside in the IP prefix allocated to the account.

The few seconds Cloudflare requires to iterate over the CNAME can cause a slight downtime. This is likely acceptable for CNAME verification of Custom Hostnames for staging or development sites. However, Cloudflare recommends verification of Custom Hostnames via TXT record or HTTP token for live production traffic. When TXT or HTTP verification completes and the Custom Hostname shows Active in the Cloudflare SSL/TLS app under the Custom Hostnames tab, inform your customer to CNAME traffic to Cloudflare.

​TXT

Each API call to create a Custom HostnameOpen external link provides a TXT ownership_verification record for your customer to add to their DNS for ownership validation of the Custom Hostname.

{  "result": [    {      "id": "3537a672-e4d8-4d89-aab9-26cb622918a1",      "hostname": "app.example.com",      // ...      "status": "pending",      "verification_errors": [        "custom hostname does not CNAME to this zone."      ],      "ownership_verification": {        "type": "txt",        "name": "_cf-custom-hostname.app.example.com",        "value": "0e2d5a7f-1548-4f27-8c05-b577cb14f4ec"      },      "created_at": "2020-03-04T19:04:02.705068Z"    }  ]}

​HTTP

Each API call to create a Custom Hostname also provides an HTTP ownership_verification record. Compared to TXT verification, HTTP verification doesn’t require your customer to change their DNS. HTTP verification is used mainly by organizations with a large deployed base of custom domains with HTTPS support. Serving the HTTP token from the zone's origin server allows hostname verification before proxying domain traffic through Cloudflare.

To get and use an HTTP ownership_verification record:

1. Make an API call to create a Custom HostnameOpen external link.

2. In the response, copy the http_url and http_body from the ownership_verification_http object:

   Example response (truncated)

   {  "result": [    {      "id": "24c8c68e-bec2-49b6-868e-f06373780630",      "hostname": "app.example.com",      // ...      "ownership_verification_http": {        "http_url": "http://app.example.com/.well-known/cf-custom-hostname-challenge/24c8c68e-bec2-49b6-868e-f06373780630",        "http_body": "48b409f6-c886-406b-8cbc-0fbf59983555"      },      "created_at": "2020-03-04T20:06:04.117122Z"    }  ]}

3. Store the http_url and http_body on your origin web server.

   Example configuration

   location "/.well-known/cf-custom-hostname-challenge/24c8c68e-bec2-49b6-868e-f06373780630" {  return 200 "48b409f6-c886-406b-8cbc-0fbf59983555\n";}

4. After a few minutes, you will see the hostname validation become Active in the UI.

​Error codes

Various hostname verification errors include:

​Verification statuses

Applicable hostname verification status includes: