check dns-blacklist of ip by using namp - nmap

Question

I'm talking about this script for nmap
http://nmap.org/nsedoc/scripts/dns-blacklist.html
User Summary
Checks target IP addresses against multiple DNS anti-spam and open proxy blacklists and returns a list of services for which an IP has been flagged. Checks may be limited by service category (eg: SPAM, PROXY) or to a specific service name.
Does it possible to use Timing and Performance of nmap like make it in parallel and set time out? any example please?
Thank you

Answer 1

The dns-blacklist script uses the dnsbl library to perform queries. That library uses Lua coroutines to issue many requests in parallel. The number of coroutines (including scripts) that can be running at any given time is set by the CONCURRENCY_LIMIT variable in nse_main.lua, and is not settable by the user. A more complete description of NSE parallelism can be found in the online documentation.
For timeouts, the script itself does not accept a timeout script-argument. Fortunately, though, the dnsbl library offloads the DNS query execution to the dns library, which has a function called get_default_timeout:
get_default_timeout = function()
local timeout = {[0] = 10000, 7000, 5000, 4000, 4000, 4000}
return timeout[nmap.timing_level()] or 4000
end
This shows that the dns library will set the timeout for DNS queries to 4000 ms (4 seconds) for -T3 (the default) through -T5, but will be more cautions at lower timing levels.