Ping response produces ? unknow packet type randomly

[john.wright]

    This is the DNS server of our ISP vendor. The people at the site are reporting slow repsonse.  When I ping from our firewall outside I get ? someplace within the standard 5 packet ping.

Any ideas what may be going on?   

mbny1fw50# ping 24.29.99.35

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 24.29.99.35, timeout is 2 seconds:

?!!!!

Success rate is 80 percent (4/5), round-trip min/avg/max = 1/7/10 ms

Inside ping is fine.

mbny1fw50# ping 10.94.2.238

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.94.2.238, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/10 m mbny1fw50# ping 10.94.2.238

[John Blakley]

What happens if you try to ping the ip while sourcing from the inside interface or from an inside host? Do you lose packets?

HTH,
John

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[Richard Burts]

In this situation I am not sure that the ? represents an unknown packet type. On ASA the ? is a failed/time out ping attempt.

In my experience when you attempt ping sometimes the first ping request will fail and the other work (which is the pattern shown in this post). Frequently the explanation for this is that the firewall needed to arp when it attempted the first ping and the first ping times out. After that there is an entry in the arp table and the other pings succeed. I wonder if that is what is going on here.

HTH

Rick