Quoting from the web site at https://dnsflagday.net/ What is happening? The current DNS is unnecessarily slow and suffers from inability to deploy new features. To remediate these problems, vendors of DNS software and also big public DNS providers are going to remove certain workarounds on February 1st, 2019. This change affects only sites which operate software which is not following published standards. Are you affected? On that web page, there is a Domain Owner's test. You can enter a domain name and click 'test' and shortly receive a report of what was found regarding your domain's DNS servers. I somehow managed to miss the announcement of this upcoming event, even though I read this mailing list fairly closely. Perhaps it was announced somewhere else instead. I think it needs to be mentioned here if it hasn't already been. - Brian