few calls are failing throwing "java.net.UnknownHostException" from docker instance after some attempt again working fine

  docker, dsn, java, rest

We are using docker based container alpine docker image and rest template an API client. while running the load test few calls are failing throwing "java.net.UnknownHostException". Read some article in web, They are suggesting

RUN sed -i ‘s/networkaddress.cache.negative.ttl=10/networkaddress.cache.negative.ttl=0/’ /usr/lib/jvm/default-jvm/jre/lib/security/java.security

Its says If the value is zero, then another dns lookup will be tried and most likely it will succeed. My question is why the URL is missing from the DNS in the first place.

Source: Docker Questions