PowerDNS - Definition and Overview

PowerDNS is a versatile DNS server, written in C++ and licensed under the GPL. It runs on most Unix derivatives and on Microsoft Windows. PowerDNS features a large number of different backends ranging from simple BIND style zonefiles to relational databases and load balancing/failover algorithms. A DNS recursor is also included as a separate program.

Features

PowerDNS consists of a single core, and multiple dynamically loadable backends that run multi-threaded. The core handles all packet processing and DNS intelligence, while one or more backends deliver DNS records using arbitrary storage methods.

Zone transfers and update notifications are supported, and the processes can run unprivileged and chrooted. Various caches are maintained to speed up query processing. Runtime control is available through the pdns_control command, which allows reloading of separate zones, cache purges, zone notifications and dumps statistics in MRTG format. Realtime information can also be obtained through the optional built-in web server.

The pdns recursor is a resolving DNS server, that runs as a separate process. The main pdns server can be configured to proxy recursive queries to the recursor, and optionally overlay authoritative zone data.

Backends

Currently, the following backends are included in the main PowerDNS distribution:

Pipe backend 

queries a separate process for answers corresponding to DNS queries through a standard Unix pipe

Generic SQL backends 

support zone data storage in MySQL, PostgreSQL, Oracle and SQLite relational databases

DB2 backend 

queries an IBM DB2 DBMS

BIND backend 

reads zone data from regular BIND style zonefiles (in-memory)

ODBC backend 

retrieves zone information from ODBC databases (windows only)

XDB backend 

can talk to Tridge's Trivial Database, or to regular *db tables on disk (for very high performance needs)

LDAP backend 

DNS zone information out of an LDAP directory

Geo backend 

allows different answers to DNS queries coming from different IP ranges, for example based on geographic data

Random backend 

answers random data (for testing)

External links

• PowerDNS website (http://www.powerdns.com) and documentation (http://docs.powerdns.com)
• Open Source Community page (http://www.ds9a.nl/powerdns.org/)
• Preliminary GeoBackend documentation (http://cvs.blitzed.org/geo-dns/README?rev=HEAD&content-type=text/vnd.viewcvs-markup)