# Testing Unicast Discovery

In order to test unicast discovery, the testing tool launches its own mock DNS server which your Node will need to be pointing at in order to correctly discover the mock registries. The following steps should be completed to operate in this mode:

*   Ensure the `DNS_SD_MODE` in the testing tool's `nmostesting/UserConfig.py` file is set to `'unicast'` before running the tool.
*   Configure the DNS search domain for your Node to be `testsuite.nmos.tv` (either manually or by providing this to your Node via DHCP).
*   Configure the DNS server IP address for your Node to be the IP address of the host which is running the testing tool (either manually or by providing this to your Node via DHCP).

Unicast DNS advertisements for registries only become available once tests are running. As a result the unit under test may need prompting to re-scan the DNS server for records at this point. The `DNS_SD_ADVERT_TIMEOUT` config parameter may be used to increase the period which the test suite waits for in this situation.

If your network requires the use of the proxy server, you may find it necessary to disable this configuration on the host running the testing tool and on the unit under test when using unicast DNS. This is because any requests to fully qualified hostnames are likely to be directed to your proxy server, which will be unable to resolve them.
