Packet Tracer question: First PDU often fail. Why?

workfrom925

For experts here who has Packet Tracer. When I add a simple PDU to test out host connectivity, the first try often fail. The second try would succeed. This happens a lot. I don't think it's a bug with Packet Tracer. So why?

Also, I assume adding a simple PDU is the same as ping, right?

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Ltat42a

The first PDU fails because of the ARP request that happens in a network. The ARP translates an IP address into a MAC address. During this process, there is a delay in the ICMP (ping) request. Same thing happens when you do a simple ping on live gear. Often times the first ping will return at 60-80%. Ping it again and the reply comes back at 100%.

hth