[e2e] RES: What's wrong with this picture?

David P. Reed dpreed at reed.com
Tue Sep 8 04:58:19 PDT 2009



On 09/08/2009 02:02 AM, Stjepan Gros wrote:
> But it is interesting that the first ping command has been running for
> slightly more than 33 seconds and during that time it only sent 24
> probes, instead of at least 30 (one per second)?
>
>    
Good observation - I missed this data point. I can only suggest that the 
"ping" equivalent called "DNS lookup" took a full roundtrip (many 
seconds), and the once per second rate starts after the name is 
resolved.  I didn't do a confirming experiment, because I didn't notice 
that.  It was the first time I named "lcs.mit.edu" in my session, so I 
doubt it was in my DNS cache.



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