A/AAAA or CNAME?

In D(omain) N(ame) S(ystem) settings CNAME refers to a domain name.
There are aspects to using CNAME that can improve your knowledge:

  • ‘example.com CNAME www.example.com’ is blocked by my hosting provider. This does not fit with their earnings model. A / AAAA is a general way out here.
  • CNAME requires slightly more search time; security tests are more complicated; a low security risk is mentioned.
  • When using A / AAAA you can inconsistently refer to IPs / servers with or without www..
  • ‘www.example.com CNAME example.com’ replaces an early, not really safe, ‘Force Redirect’ in the DirectAdmin control panel.
  • For incoming email in MX settings, ‘mail.example.com’ is more stable than ‘example.com’. In case of relocation of the website, the email traffic is not affected. Email client Outlook also defaults with ‘mail.example.com’.
  • Proper use of CNAME for DMARC at rijksoverheid.nl, see dnsspy.io. The false alarm in this tool has been addressed.