Use the ping URL command to verify that the Dgraph process is running on a given host name and port number.
http://hostname:port/admin?op=ping
http://localhost:5555/admin?op=ping
dgraph Web07-WIN:5555 responding at Mon Sep 26 09:27:43 2011
If the MDEX Engine is not running, then your browser will display an error message saying that it cannot establish a connection.