Maandelijks archief: maart 2015

How to resolve DNS queries using different DNS servers & without DNS forwarding

If you ever run in the issue were you have two different DNS servers that are both responsible to resolve different records and you are not allowed to configure DNS forwarding. You can use the following procedure on your Linux, Unix based distro:

 

  1. cd /usr/bin
  2. cp nslookup nslookup.orig
  3. rm nslookup
  4. vi nslookup
#!/bin/bashHOSTNAME=${1}

if [[ $HOSTNAME = 192.168.2* ]]; then

/usr/bin/nslookup.orig $HOSTNAME 192.168.2.110

elif [[ $HOSTNAME = *rsa.lab ]]; then

/usr/bin/nslookup.orig $HOSTNAME 192.168.2.110

else

/usr/bin/nslookup.orig $HOSTNAME 8.8.8.8

fi

  1. chmod 777 nslookup

As a result, internal IP addresses staring with 192.168.2.* and hostnames containing *.rsa.lab where resolved by the DNS server with IP 192.168.2.110 whilst everything else got resolved by the DNS server with IP 8.8.8.8.