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DNS Query: Authoritative vs Non-Authoritative Responses

November 9, 2014 by @HKw@! | No Comments | Filed in DNS

I believe most of your used nslookup command to query  particular DNS record. Sometime, the nslookup return result with “Non-authoritative answer” follow by a list of nameservers. What “Non-authoritative answer” referring to?

When we sending DNS query to DNS Server, DNS server can provides either an authoritative or a non-authoritative response to the client query.

Below are the differences between Authoritative Responses and Non-Authoritative Responses

Authoritative

– An authoritative response is one in which the server returns an answer that it knows is correct, because the request is directed to the authoritative server that manages the domain. An DNS server is authoritative when it hosts a primary or secondary copy of a DNS Zone.

Non-authoritative

– A non authoritative response is one in which the DNS server that contains the requested domain in its cache answers a query by using forwarders or root hints. Because the answer provided might not be accurate (only authoritative DNS server can issue that domain information), it is called a non-authoritative response.

Troubleshooting DNS issue with Nslookup command

October 18, 2014 by @HKw@! | No Comments | Filed in DNS, Linux, Mac OS X, Unix, Windows

When troubleshooting DNS problem, Nslookup is used to perform DNS queries and to examine the contents of zone files on local and remote servers.

Nslookup is a standard command-line tool which available on Windows, Linux and Mac OS platform. Nslookup offers you the ability to perform query testing of DNS servers and to obtain detailed responses at the command prompt.

To use nslookup in command-line mode, enter the following in the command prompt window:

nslookup DNS_name_or_IP_address server_IP_address

This command will look up a DNS name or address using a server at the IP address you specify.”

Here i going to show few examples on using the nslookup command. (more…)