THIS SERVICE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
The query service is implemented as a simple DNS service. In order to support evaluation of different alternatives, the service provides both TXT and A record based queries. The query process has three steps:
- Identify the longest PSD by removing one label from the organizational domain (i.e. com for example.com)
- Append psddmarc.org to the end of the longest PSD (i.e. com.psddmarc.org for the example above)
- Perform a DNS query for type A or TXT for that name
If any result other than nxdomain, a DNS error (temporary or permanent), or status: NOERROR and ANSWER: 0 is returned, then the PSD may be a PSD DMARC participant and recievers that participate in PSD DMARC may (for testing purposes only) wish to query for a PSD DMARC record for that longest PSD.
Note: The only time NOERROR and ANSWER: 0 should be returned is for queries that are not for the longest PSD (e.g for 'uk' instead of '.gov.uk'). Properly formed queries will return nxdomaon for non-PSD DMARC domains.