PDNS has the concept of backends and modules. Non-static PDNS distributions have the ability to load new modules at runtime, while the static versions come with a number of modules built in, but cannot load more.
Related parameters are:
Outputs all known parameters, including those of launched backends, see below.
Launches backends. In its most simple form, supply all backends that need to be launched. If you find that you need to launch single backends multiple times, you can specify a name for later instantiations. In this case, there are 2 instances of backend1, and the second one is called 'name'. This means that --backend1-setting is available to configure the first or main instance, and --backend1-name-setting for the second one.
If backends are available in nonstandard directories, specify their location here. Multiple files can be loaded if separated by commas. Only available in non-static PDNS distributions.
Will list all available modules, both compiled in and in dynamically loadable modules.
$ /usr/sbin/pdns_server --launch=gpgsql --help=gpgsql