bhai jab me koi bi java chatroom open krta hoo to ye error aa raha hay baar baar.

[20:38] Unable to connect : java.net.UnknownHostException : chat.tafreeh.net
[20:38] Unable to connect : java.net.UnknownHostException : chat.tafreeh.net
[20:38] Unable to connect : java.net.UnknownHostException : chat.tafreeh.net

ye error q aa raha hay, iska koi solution bataiye plz