CAA Record and why it is needed (SSL related)

What is CAA record and how it works

How to set up the CAA for the domain using Namecheap Basic/FreeDNS/PremiumDNS

Nowadays, when almost everyone embraces HTTPS, a lot of fraud attempts which can lead to certificate mis-issuances may occur.

To prevent this, the CAB Forum with assistance of IETF found a solution - CAA record.


Certification Authority Authorization (CAA) is a DNS record, which allows a domain name holder to specify the preferred Certification Authorities (CAs) to issue certificates for that domain, hence making no other CAs authorized to do that.

On February 22nd, 2017, CAA checks were made mandatory due to the CAB ballot. More details can be found here .

Thus now, before issuing a certificate for some domain, CAs have to check this domain for any CAA records present, and decline the issuance if a CAA record is set up with another CA preference. However, if there is no CAA record set up, they are still allowed to issue one.

Now we can see that reasons behind using a CAA record can be the following:

- You want to limit your domain to be issued a certificate only by your trusted certificate authorities.
- You want a Certificate Authority to implement additional checks to reduce the risk of unintended certificate mis-issue.

There are some types of CAA records with different parameters which have their own different purposes. They are described below:

example.com. IN CAA 0 issue "comodoca.com"

The CAA record set up above allows the Comodo CA (now Sectigo CA) to be an issuer of certificates for example.com.

Please note that a CAA record with no CA specified under the ‘issue’ parameter will restrict certificate issuance for the domain name in question: paragraph 5.2

Also, keep in mind that setting up one CA in the preferred by you format may lead to a rejected certificate issuance attempt from another one.

example.com. IN CAA 0 issuewild "comodoca.com"

This record above pretty much allows the same, but it should be used when a wildcard certificate is going to be issued for the example.com domain.

example.com. IN CAA 0 iodef "mailto:admin@example.com"
example.com. IN CAA 0 iodef "https://admin.example.com"

The ‘iodef’ record is the record which defines the way domain holder will be notified in case of any issuance policy violation spotted by Certificate Issuer.

In order to set up the desired CAA Record you should check if your DNS provider allows CAA Record implementation. This link (https://sslmate.com/caa/support) can be helpful.

If you use Cloudflare, CAA records can be set up there as well. You can find the guide at https://support.cloudflare.com/hc/en-us/articles/115000310792-Configuring-CAA-Records-

This tool might be used to generate the CAA record.

Additional information about how CAA treats different types of domain pointing can be found here.

Notes:

  • If your domain is pointed to Namecheap Backup DNS, it is not possible to create a CAA record in the "Advanced DNS" section of Namecheap account panel. Though, if the domain is using Namecheap Basic, Premium DNS or FreeDNS, such a record can be added via "Advanced DNS" as described in the following section.
  • If it is pointed to Namecheap Web Hosting DNS, the record can be added via DNS zone via both cPanel and WHM, the record settings for cPanel can be found here.
  • To create the record via API, please follow this guide.

How to set up the CAA for the domain using Namecheap Basic/FreeDNS/PremiumDNS

  • Sign into your Namecheap account (The Sign In option is available in the top hat of the page).
  • Select Domain List from the left sidebar and click on the Manage button next to your domain.

caa_login_manage

  • Navigate to the Advanced DNS tab at the top of the page.

caa_advanced

  • Find the Host records section and click on the Add New Record button.

add-new-caa

  • Select CAA Record for Type.

caa_rec_type

  • Specify the corresponding domain name or subdomain in the Host field.

caa_host

  • Select the required Tag value from the drop-down.

caa_tag

Note: The Tag can be one of the following values:

  issue - Is mostly used for a single-domain certificate and applies to domain (@) or subdomain specified in Host field.

  issuewild - Is mostly used for the wildcard certificates and applies to the domain (@) specified in Host field and all its subdomains.

  iodef - Is used along with the corresponding email address specified in Value and this contact is to be used by a CA to notify a client if any issuance policy violation spotted by this CA.

  • Specify "comodoca.com" in Value field for all Comodo (now Sectigo) certificates.

caa_value

Note: Both "sectigo.com" and "comodoca.com" Values work at the moment for Sectigo (former Comodo) certificates.

  • Save changes by clicking on Save All Changes.
  • That’s it!

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