# MA-713.012019: MyCERT Advisory - DNS Flag Day

**Date:** 30 Jan 2019  
**Source:** https://www.mycert.org.my/portal/advisory?id=MA-713.012019  
**Advisory ID:** MA-713.012019

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**1.0    Introduction**
MyCERT received information from valid sources that beginning 1st February 2019, major DNS software vendors will stop supporting for any server that violates both the DNS RFC 6891 and RFC 2671 standard. As a result servers that do not response to the queries with EDNS extensions will stop functioning and become inaccessible. As such, operators of DNS servers need to ensure the users are not facing difficulties for the upcoming scheduled maintenance. The authoritative server operators need to ensure the implementations can response correctly to the queries of EDNS extensions by 31 January 2019 without any issue.
**2.0    Impact**
•    Some domains will become solidly unreachable.
•    Services may become intermittently unavailable due to variable authoritative server behavior and how resolvers cache this.
**3.0 Affected Products/Systems**
The following versions of DNS resolvers will not accommodate EDNS non-compliant responses:
•    BIND 9.13.3 (development) and 9.14.0 (production)
•    Knot Resolver has already implemented stricter EDNS handling in all current versions
•    PowerDNS Recursor 4.2.0
•    Unbound 1.9.0
**4.0 How to check the Status of your Domain**
User can browse to <https://dnsflagday.net/> to check on the status of their domain and take necessary action based on the result of their domain status.
**5.0 Recommendations**
•    Running and update current versions of DNS software.
•    Ensure that name server implementation correctly responds to queries with EDNS extensions.
•    Domain holders need to consult with their DNS operator for further assistance.
Generally, MyCERT advises any 
For further enquiries, please contact MyCERT through the following channels:
E-mail: [[email protected]](/cdn-cgi/l/email-protection#c6a5bfa4a3b4ffffff86a5bfa4a3b4b5a3a5b3b4afb2bfe8abbf) or [[email protected]](/cdn-cgi/l/email-protection#5c31253f392e281c31253f392e2872332e3b723125)
Phone: 1-300-88-2999 (monitored during business hours)
Fax: +603 89453442
Mobile: +60 19 2665850 (24x7 call incident reporting)
SMS: CYBER999 REPORT EMAIL COMPLAINT to 15888
Business Hours: Mon - Fri 09:00 AM - 18:00 PM MYT
Web: <https://www.mycert.org.my>
Twitter: <http://www.twitter.com/mycert>
Facebook: <http://www.facebook.com/mycert.org.my>
Cyber999 Mobile Apps: [IOS Users](https://itunes.apple.com/my/app/cyber999-mobile-application/id888552400?mt=8&ign-mpt=uo%3D4) or [Android Users](https://play.google.com/store/apps/details?id=my.cyber999.mobile)
**5.0    References**
•    [https://dnsflagday.net/]( https://dnsflagday.net/ )
•    <https://blog.apnic.net/2019/01/17/are-you-ready-for-dns-flag-day/>