DNS configuration#

As explained in Documenting, documentation for PyAnsys libraries is published online following canonical name (CNAME) convention:


To request a CNAME for the pyansys.com domain, contact the PyAnsy core team. They handle the creation of all PyAnsys subdomains.

Once the CNAME is created, repository administrators can configure their published documentation in GitHub pages to be exposed through it. To configure the CNAME for your documentation, see Managing a custom domain for your GitHub Pages site in the GitHub documentation.

DNS TXT verification#

Once a CNAME is registered under the pyansys.com domain, the next step is to perform a DNS TXT verification. All PyAnsys subdomains are required by the Ansys IT department to provide a DNS TXT verification. To verify a new CNAME for an organization, see Verifying a domain for your organization site in the GitHub documentation. This article shows how to create DNS TXT verification elements for GitHub Pages sites.


Only users with privilege access to the pyansys.com DNS zone can perform a DNS TXT verification. If assistance is needed, contact the PyAnsy core team.

PyAnsys-verified domains#

In the Ansys GitHub organization, these domains have been verified:

  • pyansys.com

  • docs.pyansys.com


Only CNAME requests with one subdomain before the previous verified domains are allowed. For more information, see DNS protection measures.

DNS protection measures#

The rationale behind choosing the previous CNAME convention is related to cybersecurity. As the Verifying a domain for your organization site article explains, GitHub provides for verifying domains for users and organizations.

Having a verified domain prevents users external to the organization from taking over existing direct subdomains.

However, GitHub does not verify deeper subdomains.

This is better explained with the following examples:

Scenario for a protected subdomain#

  • The docs.pyansys.com domain has been verified for the Ansys GitHub organization.

  • This CNAME is requested: subdomain.docs.pyansys.com.

This CNAME can only be used by repositories inside the Ansys GitHub organization. Any attempt by an external user to take over this CNAME is identified and rejected by GitHub.

Scenario for a vulnerable subdomain#

  • The domain docs.pyansys.com has been verified for the Ansys GitHub organization.

  • This CNAME is requested: subsubdomain.subdomain.docs.pyansys.com.

This CNAME can be used by external users for their repositories. For this reason, you must avoid creating CNAME requests that are not verified by the Ansys GitHub organization.

CNAME takeover prevention#

CNAME values have been taken over in the past by external users, typically due to these reasons:

  • The Ansys GitHub organizations had no domain verification set up.

  • A CNAME created did not follow the recommended CNAME guidelines.

  • More than one level of subdomain depth under the verified domain had been requested.

  • Long time lapses occurred between CNAME creation and assignment to GitHub pages.

Thus, it is important that you follow these guidelines:

  • Ensure that your GitHub organization has verified domains for hosting GitHub pages.

  • Check that the CNAME that you request does not have a subdomain depth larger than one with respect to the verified domains.

  • Request a CNAME only when needed, which is just prior to publishing the site.

  • Request deletion of the CNAME once it is no longer used to prevent others from hosting their sites on it.