A DNS zone is usually served by multiple authoritative servers, which is actually recommended for the sake of redundancy. Large authoritative DNS operators even combine different name server implementations to avoid complete infrastructure outage in case of any software error. For synchronizing zone contents between authoritative servers, a DNS-specific mechanism is available, called zone transfer. It is well established and supported by all common DNS implementations. It enables both full zone transfer (AXFR) and incremental update (IXFR).
A global DNS maintenance is scheduled for February 1, 2019, and authoritative server operators must get ready for it. That is why we dedicate our today’s article to the state of readiness of .CZ domains for changes that will be effective from the beginning of next month.
We are releasing dns-collector, an entry part of our pipeline for monitoring of our DNS servers and analysis of the DNS traffic. Together with advanced analysis of the collected data, we can not only monitor the DNS traffic for urgent problems, but also detect and examine long-term trends and issues (e.g. misconfiguration of other servers). We have presented this system at the IT 15.2 conference (video and slides in Czech).
In mid-February we informed about Reducing TTL in the .cz zone by one hour. Then, at a similar hour every Wednesday, we reduced it by another hour, until on March 15, 2017 we reached the required value of 1 hour (i.e. TTL=3600).