DNS testing and caching¶

Overview¶

Sometimes, domain names resolution problems may lead to streams publishing/playback stopping on a server, for example, if backend server name used for REST hooks handling cannot be resolved. Since WCS build 5.2.1707 DNS may be tested periodically to detect a such problems. Also, addresses caching may be forced to decrease Java machine DNS resolver load.

DNS testing configuration¶

DNS testing may be enabled by the following parameters:

dns_test_enable=true
dns_test_name=google.com

The settings are applied after WCS restart. The DNS name defined is resolved every 60 seconds. If the name is not set, it will not be tested. If the name cannot be resolved, Unknown host warning will be displayed in server log.

DNS testing results displaying¶

DNS testing results are displayed on server statistics page

curl -s 'http://localhost:8081/?action=stat&params=dns_resolution_time'

A minimum, average and maximum DNS reply times are displayed in milliseconds

-----Network Stats (Mbit/s)-----
dns_resolution_time=53/59/65

Addresses cache configuration¶

Resolved addresses cache may be forced by the following parameter

enable_network_address_cache=true

The setting is applied after WCS restart. Cache interval is not limited in this case.