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DNS Flag Day - Disabling some DNS compatibility features

This document (7023663) is provided subject to the disclaimer at the end of this document.


SUSE Linux Enterprise Server 10
SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 15


Administrators operating DNS (Domain Name System) servers are potentially being affected by the DNS Flag Day.

The operators of the world DNS infrastructure will switch to a stricter handling of EDNS0 flagging, and servers that are improperly firewalled or misbehave will no longer considered to be working in the worlds DNS infrastructure.

While most regular DNS software supports this for a long time, firewall appliances might filter the EDNS0 requests incorrectly.

The website links to an online compliance tester to check if your site is set up correctly, both software and firewall wise. The focus here is more around  EDNS0 
The website links to an online compliance tester checking all the features of EDNS.


SUSE already ships ISC (Internet Systems Consortium) BIND (Berkeley Internet Name Domain) 9 versions in SUSE Linux Enterprise 10 and newer and these versions are compliant with the wanted EDNS0 flag usage.


Stricter handling of the EDNS0 requests.

Additional Information

For  more information about DNS Flag Day - February 1, 2019, please see  the ISC details here.


This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7023663
  • Creation Date: 23-Jan-2019
  • Modified Date:03-Mar-2020
    • SUSE Linux Enterprise Server

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