How to call authoritative server for ip response?

Question

I have cached the response received from dig command using a c code , and I want to use authorities list to call directly for finding the ip ,avoiding a part of dns lookup , but I have no idea how to do that.

;; AUTHORITY SECTION:
gogole.com.     172748  IN  NS  ns2.google.com.
gogole.com.     172748  IN  NS  ns3.google.com.
gogole.com.     172748  IN  NS  ns1.google.com.
gogole.com.     172748  IN  NS  ns4.google.com.

;; ADDITIONAL SECTION:
ns2.google.com.     104506  IN  A   216.239.34.10
ns1.google.com.     345589  IN  A   216.239.32.10
ns3.google.com.     104506  IN  A   216.239.36.10
ns4.google.com.     104506  IN  A   216.239.38.10

For example this is for google , I want to interrogate ns1.google.com next time to have the ip. Can anyone help me ? Thanks.

Answer 1

the Linux dig command's syntax is described in its manual page

man dig

This will tell you that:

A typical invocation of dig looks like:

    dig @server name type

where:

server
    is the name or IP address of the name server to query.
    This can be an IPv4 address in dotted-decimal notation
    or an IPv6 address in colon-delimited notation (...)

So, once you have the authoritative name server's name or IP address you want to query, e.g. ns1.google.com as shown in your example, you just add @ns1.google.com to your dig command-line to obtain the response from that server.

for instance, like this:

dig @ns1.google.com google.com A

This is useful to check the TTL set by the owner of the zone for that DNS record, and to troubleshoot DNS cache problems.