.. SPDX-License-Identifier: GPL-3.0-or-later .. _mod-http-trace: Debugging a single request ========================== Using query policies -------------------- Query policies :any:`policy.DEBUG_ALWAYS`, :any:`policy.DEBUG_CACHE_MISS` or :any:`policy.DEBUG_IF` can be used to enable debug-level logging for selected subdomains or queries matching specific conditions. Please refer to :ref:`mod-policy-logging` for more information. Using HTTP module ----------------- The :ref:`http module ` provides ``/trace`` endpoint which allows to trace various aspects of the request execution. The basic mode allows you to resolve a query and trace debug-level logs for it (and messages received): .. code-block:: bash $ curl https://localhost:8453/trace/e.root-servers.net [ 8138] [iter] 'e.root-servers.net.' type 'A' created outbound query, parent id 0 [ 8138] [ rc ] => rank: 020, lowest 020, e.root-servers.net. A [ 8138] [ rc ] => satisfied from cache [ 8138] [iter] <= answer received: ;; ->>HEADER<<- opcode: QUERY; status: NOERROR; id: 8138 ;; Flags: qr aa QUERY: 1; ANSWER: 0; AUTHORITY: 0; ADDITIONAL: 0 ;; QUESTION SECTION e.root-servers.net. A ;; ANSWER SECTION e.root-servers.net. 3556353 A 192.203.230.10 [ 8138] [iter] <= rcode: NOERROR [ 8138] [resl] finished: 4, queries: 1, mempool: 81952 B See chapter about :ref:`mod-http` for further instructions how to load ``webmgmt`` endpoint into HTTP module, it is a prerequisite for using ``/trace``.