Ipv6 DNS error message

["Paul Jenkins" <pjenkins () dsci com>]

All-

New to the list so I'm not sure if this has been discussed but her goes:

While running various scans and comparing the output and functionality
between the Ipv4 and Ipv6 scans I noted the insane difference in the
amount of time it takes for the ipv6 scan to run on a windows box.
Example for 20 IP addresses it would take in the neighborhood of an hour
and a half for a Nmap default scan. While running through the -sP
-PS(ports) options I was watching wireshark, and noticed the scan was
over quickly but there was still some chatter on the line. DNS requests
lots of them to various v6 IP's on the same net work. I do not have a
DNS set up, it's not necessary for my application, the v4 scan quickly
displays a "mass_dns:" error and merrily goes about it's scan, ipv6 has
no such error and leaves the operator waiting. Originally I thought
maybe it was due to the ipv6 packets not being crafted in the Nmap
program, but Linux blasts right through the scan with no qualms, which
left me wondering why. Now with the -n switch scans are quick and
painless.

My question is why does v6 wait for dns resolution for so long, where v4
says no dns fine so be it.

Paul 
~Someone is always listening, whether or not you want them to. ~


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