I second Parallel::ForkManager. I've got a nifty little ssh tool that uses it, and has good control.

If you need 1 second and not 2, you may have some problems (in general) with resolution.

Finally, note that nslookup has an interactive mode for multiple lookups, which also takes command line options, such as -timeout=1. Using these options gives great results on a list of 50, even for non-existent hosts:

time nslookup -timeout=1 -nosearch -norecurse -retry=0 -fail <<HERE
host.that.exists
host.that.doesnt
...
last.one.honest
exit
HERE
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