The resolver :ref:`library <lib_index>` leverages the `processing API`_ from the libknot to separate packet processing code
into layers. In order to keep the core library sane and coverable, there are only two built-in layers:
the :c:func:`iterate_layer`, and the :c:func:`itercache_layer`.
the :c:func:`iterate_layer`, and the :c:func:`rrcache_layer`.
*Note* |---| This is only crash-course in the library internals, see the resolver :ref:`library <lib_index>` documentation for the complete overview of the services.