a function to find the fastest free DNS server

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; }
Uses GNU Parallel.
Sample Output
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
2015-04-26 08:22:32

2 Alternatives + Submit Alt

  • 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 ; } Show Sample Output


    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 · 2011-08-18 01:11:53 1
  • http://public-dns.info gives a list of online dns servers. you need to change the country in url (br in this url) with your country code. this command need some time to ping all IP in list. Show Sample Output


    1
    curl -s http://public-dns.info/nameserver/br.csv| cut -d, -f1 | xargs -i timeout 1 ping -c1 -w 1 {} | grep time | sed -u "s/.* from \([^:]*\).*time=\([^ ]*\).*/\2\t\1/g" | sort -n | head -n1
    glaudiston · 2017-02-02 12:00:38 0

What Others Think

Had to use "--gnu" option to parallel.
bartonski · 165 weeks and 4 days ago

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