a function to find the fastest DNS server

• a function to find the fastest free DNS server

  Uses GNU Parallel.

  This is sample output - yours may be different.

  208.67.222.222 ;; Query time: 18 msec
  208.67.220.220 ;; Query time: 18 msec
  198.153.194.1 ;; Query time: 22 msec
  8.8.8.8 ;; Query time: 14 msec
  8.8.4.4 ;; Query time: 18 msec
  156.154.70.1 ;; Query time: 27 msec
  198.153.192.1 ;; Query time: 42 msec
  156.154.71.1 ;; Query time: 33 msec

  
  

  8
  timeDNS() { parallel -j0 --tag dig @{} "$*" ::: 208.67.222.222 208.67.220.220 198.153.192.1 198.153.194.1 156.154.70.1 156.154.71.1 8.8.8.8 8.8.4.4 | grep Query | sort -nk5; }
  unixmonkey74668 · 2015年04月26日 08:22:32 31
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• a function to find the fastest free DNS server

  Evoke from the command like as: timeDNS commandlinefu.com . This isn't too terribly practical, but it is a good code example of using subshells to run the queries in parallel and the use of an "anonymous function" (a/k/a "inline group") to group i/o. . I'm assuming you have already defined your local DNS cache as ${local_DNS}, (here, it's 192.168.0.1). . You do need to install `moreutils` to get `sponge`. . If you're willing to wait, a slower version w/o sponge, (and w/o sorting), is this: . DNS () { for x in "192.168.0.1" "208.67.222.222" "208.67.220.220" "198.153.192.1" "198.153.194.1" "156.154.70.1" "156.154.71.1" "8.8.8.8" "8.8.4.4"; do (echo -n "$x "; dig @"$x" "$*"|grep Query) ; done ; }

  This is sample output - yours may be different.

  $ timeDNS commandlinefu.com
  192.168.0.1 ;; Query time: 2 msec
  208.67.222.222 ;; Query time: 13 msec
  198.153.192.1 ;; Query time: 17 msec
  208.67.220.220 ;; Query time: 17 msec
  156.154.71.1 ;; Query time: 18 msec
  8.8.8.8 ;; Query time: 20 msec
  156.154.70.1 ;; Query time: 22 msec
  8.8.4.4 ;; Query time: 22 msec
  198.153.194.1 ;; Query time: 27 msec
  

  
  

  1
  timeDNS () { { for x in "${local_DNS}" "208.67.222.222" "208.67.220.220" "198.153.192.1" "198.153.194.1" "156.154.70.1" "156.154.71.1" "8.8.8.8" "8.8.4.4"; do ({ echo -n "$x "; dig @"$x" "$*"|grep Query ; }|sponge &) done ; } | sort -n -k5 ; }
  unixmonkey365 · 2011年08月18日 01:11:53 7
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