this page explains things better: https://www.isc.org/blogs/dns-flag-day/ https://www.isc.org/blogs/dns-flag-day/ A number of DNS software and service provider

this page explains things better: https://www.isc.org/blogs/dns-flag-day/ https://www.isc.org/blogs/dns-flag-day/ A number of DNS software and service providers have announced that we will all cease implementing DNS resolver workarounds to accommodate DNS authoritative systems that don’t follow the EDNS protocol. Domains served by DNS servers that are not compliant with the standard will not function reliably after February 1, 2019, and may become unavailable. If your company’s DNS zones are served by non-compliant servers, your online presence will slowly degrade or disappear as ISPs and other organizations update their resolvers. When you update your own internal DNS resolvers to versions that don’t implement workarounds, some sites and email servers may become unreachable. Why make this change now? Extension Mechanisms for DNS were specified in 1999, with a minor update in 2013, establishing the ‘rules of the road’ for responding to queries with EDNS options or flags. Despite this, some implementations continue to violate the rules. DNS software developers have tried to solve the problems with the interoperability of the DNS protocol and especially its EDNS extension (RFC 6891 standard) by various workarounds for non-standard behaviors. This is not unlike the way a driver with the right-of-way might hesitate at an intersection before proceeding if there were another driver in the intersection behaving erratically. These workarounds excessively complicate DNS software and are now also negatively impacting the DNS as a whole. The most obvious problems caused by these workarounds are slower responses to DNS queries and the difficulty of deploying new DNS protocol features. Some of these new features (e.g. DNS Cookies) would help reduce DDoS attacks based on DNS protocol abuse.