OnReply is a TOnReplyEvent handler triggered when a echo response is received. 

OnReply is generally used to update progress indicators or other GUI components as a result of receiving the echo response found in ReplyStatus. In TIdTraceRoute, OnReply is used to explicitly provide the host address in a ping response to the probe. 

Assign an event handler to perform additional processing when the TOnReplyEvent is triggered by Ping. 

Use ResolveHostNames to indicate if host names are resolve to an IP address prior to calling the event handler.

TOnReplyEvent