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DNS flag day logo


What is happening?

The current IPv4 is unnecessarily slow and suffers from inability to deploy new features. To remediate these problems, software vendors and also big content and access ISPs are going to remove IPv4 backwards compatibility in favor of IPv6 on February 1st, 2030.

This change affects only sites which operate software which doesn't support IPv6. Are you affected?

Site owners

Please check if your site is affected:

Test your site Domain name (without www): Your browser does not support JavaScript! Consider upgrading your browser...
<script> const domainCheckerInit = { placeIntoElement: document.getElementById( "domain-checker" ), texts: { formTitle: 'Test your site', labelText: 'Domain name (without www): ', submitText: 'Test!', reportOkHtml: ': All Ok!' + '
' + '
This site is perfectly ready, congratulations!',
	reportFailHtml: ': <span style="font-weight: bold; color: red;">Fatal error detected!</span></div>' +
	'<div><img style="height: 5em;" src="/signs/dead.svg"/></div>' +
	'<div>This site is going to STOP WORKING after the 2030 IPv4 flag day! Please retry the test to eliminate random network failures. If the problem persists you really need to request a fix from your domain administrator. You can refer them to ',

	reportTestErrorHtml: ': Test cannot be evaluated because of an error. Please make sure the domain name entered refers to a <strong>domain</strong>, i.e. use "" instead of "". Retry the test to eliminate random network failures or investigate.',
status: {
	loading: 'Testing in progress, please wait… It might take several tens of seconds.',
	done: 'Testing completed:',
	errorApi: 'Communication error! API unavailable… please try again later',
	errorInput: 'Invalid input or other unexpected error, sorry!',

}; </script>

<script src="domain-checker.js"></script>

Server operators

On or around Feb 1st, 2030, major open source software vendors will release updates that remove IPv4 backwards compatibility.

Also content and access ISPs listed below will disable backwards compatibility.

Webserver operators

For introduction to IPv6 compatibility we recommend you to use form above which produces simplified result for a whole domain.

It is also possible to test your servers directly using dig and any ping binary that supports IPv6.

The summary result of the website tests should preferably be a green message All Ok.

If there is a problem, the tool displays an explanation for each failed test. Failures in these tests are typically caused by:

  • lack of IPv6 AAAA dns record
  • broken DNS software
  • broken firewall configuration
  • bad luck

To remediate problems please upgrade your software to the latest stable versions and test again. If the tests are still failing even after a upgrade please check your firewall configuration or talk to your hosting provider.

Firewalls must not drop IPv6 packets, including unknown protocols. Modern software may deploy new protocols (e.g. DHCPv6 to protect from DoS attacks). Firewalls which drop IPv6 packets with such protocols are making the situation worse for everyone, including worsening DoS attacks and inducing higher latency for DNS traffic.

Everyone else

Make sure to use #ipv4flagday to warn everyone of the 2030 IPv4 flag day. Only if you spread the word your friends and family will be able to connect with you. Ensure to talk to your "internet provider" about IPv4 flag day. We also suggest you to take RIPE's Introduction to IPv6 course before February 1st, 2030.


Researchers and other parties like TLD operators might be interested in:

Please read respective methodologies before interpreting the data. In any case, do not hesitate to reach out to people.




They don't endorse anything on this page, but they love the internet.

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