PowerDNS is a

DNS server A name server refers to the server component of the Domain Name System (DNS), one of the two principal namespaces of the Internet. The most important function of DNS servers is the translation (resolution) of human-memorable domain names (example. ...

program, written in

C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...

and licensed under the

GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general u ...

. It runs on most

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

derivatives. PowerDNS features a large number of different ''backends'' ranging from simple

BIND BIND () is a suite of software for interacting with the Domain Name System (DNS). Its most prominent component, named (pronounced ''name-dee'': , short for ''name daemon''), performs both of the main DNS server roles, acting as an authoritative ...

style zonefiles to

relational database A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relatio ...

s and load balancing/

failover Failover is switching to a redundant or standby computer server, system, hardware component or network upon the failure or abnormal termination of the previously active application, server, system, hardware component, or network in a computer net ...

algorithms In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing c ...

. A DNS recursor is provided as a separate program.

History

PowerDNS development began in 1999 and was originally a commercial proprietary product. In November 2002, the source code was made public under the open-source GPL v2 license.

Features

PowerDNS Authoritative Server (pdns_server) consists of a single core, and multiple dynamically loadable backends that run

multi-threaded In computer science, a thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. The implementation of threads and processes dif ...

. The core handles all packet processing and DNS intelligence, while one or more backends deliver

DNS record The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned t ...

s using arbitrary storage methods. Zone transfers and update notifications are supported, and the processes can run ''unprivileged'' and ''

chroot A chroot on Unix and Unix-like operating systems is an operation that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name (and therefore normall ...

ed''. Various '' caches'' are maintained to speed up query processing. '' Run-time control'' is available through the pdns_control command, which allows reloading of separate zones, cache purges, zone notifications and dumps

statistics Statistics (from German language, German: ''wikt:Statistik#German, Statistik'', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of ...

Multi Router Traffic Grapher The Multi Router Traffic Grapher (MRTG) is free software for monitoring and measuring the traffic load on network links. It allows the user to see traffic load on a network over time in graphical form. It was originally developed by Tobias Oetik ...

rrdtool RRDtool (''round-robin database tool'') aims to handle time series data such as network bandwidth, temperatures or CPU load. The data is stored in a circular buffer based database, thus the system storage footprint remains constant over time. ...

format. Realtime information can also be obtained through the optional built-in

web server A web server is computer software and underlying hardware that accepts requests via HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiate ...

. There are many independent projects to create management interfaces for PowerDNS.

DNSSEC

The PowerDNS Authoritative Server supports

DNSSEC The Domain Name System Security Extensions (DNSSEC) are a suite of extension specifications by the Internet Engineering Task Force (IETF) for securing data exchanged in the Domain Name System (DNS) in Internet Protocol (IP) networks. The protocol ...

as of version 3.0. While pre-signed zones can be served, it is also possible to perform online signing & key management. This has the upside of being relatively easy, but the downside that the cryptographic keying material is present on the servers itself (which is also true of any HTTPS server when not used with a HSM for example).

Recursor

PowerDNS Recursor (pdns_recursor) is a ''resolving'' DNS server, that runs as a separate process. This part of PowerDNS uses a combination of native threads and user-space threads, through the use of Boost and the MTasker library,MTasker
/ref> which is a simple cooperative multitasking library. It is also available as a standalone package. It does not have to run a pdns_server process as a gatekeeper for pdns_recursor, if the goal is simply to provide caching/recursing/resolving nameservice as running pdns_recursor on its own is even more efficient than behind the authoritative component. Support for

validation was added to the pdns_recursor in version 4.0.

References

External links