Why does the traceroute command show * in its output?

Issue

• While trying traceroute to a RHEL server, the command intermittently does not return the prompt for a few seconds, and then the command shows * in its output.
• When traceroute -I is issued then this behavior and delay in output does not occur.

• While pinging to a RHEL system traceroute behaviour is different. Working as expected with Solaris and Windows.

• Traceroute is showing * in output as follows :

$ traceroute hostname 
traceroute to hostname (192.168.1.254), 30 hops max, 40 byte packets
 1  hostname (192.168.1.254)  0.353 ms  0.309 ms  0.389 ms

$ traceroute hostname 
traceroute to hostname (192.168.1.254), 30 hops max, 40 byte packets
 1  hostname (192.168.1.254)  0.336 ms *  0.379 ms