How to find a domain's authoritative nameservers(jvns.ca)

  dig ns .

   #!/bin/sh
   test $# = 1||exec echo usage: $0 domainname
   # which is the fastest stub resolver. for me dig is much slower than the others. test this yourself
   # uncomment the stub resolver to use
   #DIG="dig +norecurse";
   #DIG="drill -ord";
   #DIG="kdig +norecurse";
   #DNSQ="dnsq";
   #DNSQ="dq -a";
   if test "$DIG";then
   ns=$($DIG $1 @198.41.0.4 ns|tr '\11' '\40'|sed -n '/ NS /{s/.* //;p;q;}');
   nsip=$($DIG $ns @198.41.0.4 a|tr '\11' '\40'|sed -n '/ A /{s/.* //;p;q;}');
   $DIG $1 @$nsip ns|tr '\11' '\40'|sed -n '/./{/AUTHORITY SECTION/,/^$/{/ NS /{s/.* //;p;};};}';
   exit;
   fi;
   if test "$DNSQ";then
   ns=$($DNSQ ns $1 198.41.0.4|sed -n '/ NS /{s/.* //;p;q;}');
   nsip=$($DNSQ a $ns 198.41.0.4|sed -n '/ A /{s/.* //;p;q;}');
   $DNSQ ns $1 $nsip|sed -n '/^authority:/{/ NS /{s/.* //;p;};}';
   else sed -n '/^ *#DIG/p;/^ *#DNSQ/p;/^ *# uncomment/p' $0;
   fi 
   exit;

   198.41.0.4 is the address for the "A" root which I have memorised
   People on the internet claim it is impractical to memorise IP addresses
   I have found this is not true and knowing some of these numbers can be very useful when troubleshooting. YMMV
   Another one I have memorised is 192.5.6.30 which is the "A" com/net nameserver
   I can usually remember a 199.19.x.x org nameserver, too, such as 199.19.53.1