The release of PowerDNS Recursor 4.6, a caching DNS server responsible for recursive name resolution, is now available. PowerDNS Recursor is built on the same code base as PowerDNS Authoritative Server, but the recursive and authoritative DNS servers of PowerDNS are developed within different release cycles and are released as separate products. The project's code is distributed under the GPLv2 license.
The server provides tools for remote statistics gathering, supports instant restart, has a built-in engine for connecting handlers in Lua, fully supports DNSSEC, DNS64, RPZ (Response Policy Zones), and allows connecting blacklists. There is an option to record resolution results as BIND zone files. To ensure high performance, modern connection multiplexing mechanisms in FreeBSD, Linux, and Solaris (kqueue, epoll, /dev/poll) are used, as well as a high-performance DNS packet parser capable of handling tens of thousands of parallel requests.
In the new version:
- The 'Zone to Cache' feature has been added, which periodically fetches the DNS zone and populates the cache with its content, ensuring that the cache is always in a 'hot' state and contains data related to the zone. This feature can be used with any type of zone, including root zones. The zone can be retrieved using DNS AXFR, HTTP, HTTPS, or by loading from a local file.
- The ability to flush cache records upon receiving incoming notify requests has been provided.
- Support for encrypting DNS server queries using DoT (DNS over TLS) has been added. By default, DoT is enabled when specifying port 853 for the DNS Forwarder or by explicitly listing DNS servers through the dot-to-auth-names parameter. Certificate validation is not yet performed, nor is there automatic switching to DoT if supported by the DNS server (these capabilities will be included after approval by the standardization committee).
- The code for establishing outgoing TCP connections has been rewritten, adding the ability to reuse connections. For TCP (and DoT) connection reuse, connections are no longer closed immediately after processing the request but are kept open for a period of time (this behavior is controlled by the tcp-out-max-idle-ms setting).
- The range of metrics collected and exported with statistics and information for monitoring systems has been expanded.
- An experimental event tracing feature has been added, allowing for detailed information about the execution time of each stage of the resolving process.
Source: opennet.ru
