[dns-wg] Looking for a tool to find the fastest DNS server

On Monday, 4 August 2003, at 07:46AM, Stephane Bortzmeyer wrote:

> I'm looking for a small tool (running on Unix) that can take a list of
> DNS servers, a query to ask (such as "A ns1.nic.fr.") and which can
> print the fastest server to reply.
>
> Something like "netselect" which only exercices the kernel, not the
> actual servers, unfortunately (and which can be blocked by filters):
>
> ~ % netselect  {a,b,c,d,e,f,g,h,i,j,k,l,m}.root-servers.net
>   123 i.root-servers.net
>
> BIND9's lib/dns/resolver.c has code to do so and I wonder if someone
> extracted it in a simple tool?

#!/bin/sh
#
q=$1; shift
#
[ -z "$*" ] && echo "Syntax: $0 query server..." && exit 1
#
for m in 0 1 2 3; do
   for n in $*; do
     dig @${n} ${q};
   done
done | \
   awk '/^;; Query time:/ { qt = $4; } \
     /^;; SERVER: / { sum[$3] += qt; n[$3]++; } \
     END { for (s in sum) { print int(sum[s]/n[s]), s; } }' | \
   sort -n | head -1

[jabley at snowfall]% ./qtest.sh ". NS" a.root-servers.net 
b.root-servers.net c.root-servers.net d.root-servers.net 
e.root-servers.net f.root-servers.net g.root-servers.net 
h.root-servers.net i.root-servers.net j.root-servers.net 
k.root-servers.net l.root-servers.net m.root-servers.net
40 192.58.128.30#53(j.root-servers.net)
[jabley at snowfall]%