In our previous article, we have explained nslookup command examples and usage, which is a networking command-line tool used for querying and getting information of DNS (Domain Name System).

Here, in this article, we come up with another command line tool called dig, which is much similar to the Linux nslookup tool. We will see the usage of the dig command closely with their examples and usage.

[ You might also like: How to Install and Use dig and nslookup Commands in Linux ]

Dig stands for (Domain Information Groper) is a network administration command-line tool for querying Domain Name System (DNS) name servers.

It is useful for verifying and troubleshooting DNS problems and also to perform DNS lookups and displays the answers that are returned from the name server that was queried.

Dig is part of the BIND domain name server software suite. dig command replaces older tools such as nslookup and the host. dig tool is available in major Linux distributions.

1. Query Domain “A” Record

# <strong>dig yahoo.com</strong>

; > DiG 9.16.1-Ubuntu > yahoo.com
;; global options:  cmd
;; Got answer:
;; ->>HEADER
<p>The above command causes dig to look up the <code>"A"</code> record for the domain name <strong>yahoo.com</strong>. Dig command reads the <strong>/etc/resolv.conf</strong> file and querying the <strong>DNS</strong> servers listed there. The response from the<strong> DNS</strong> server is what dig displays.</p>
<p>Let us understand the output of the commands:</p>

• Lines beginning with ; are comments not part of the information.
• The first line tells us the version of the dig (9.16.1) command.
• Next, dig shows the header of the response it received from the DNS server.
• Next comes the question section, which simply tells us the query, which in this case is a query for the "A" record of yahoo.com. The IN means this is an Internet lookup (in the Internet class).
• The answer section tells us that yahoo.com has the IP address 98.137.11.163.
• Lastly, there are some stats about the query. You can turn off these stats using the nostats option.

2. Query Domain “A” Record with short

By default, dig is quite verbose. One way to cut down the output is to use the short option. which will drastically cut the output as shown below.

<strong># dig yahoo.com  short</strong>

98.137.11.164
74.6.231.21
74.6.231.20
74.6.143.25
74.6.143.26
98.137.11.163

Note: By default, dig looks for the "A" record of the domain specified, but you can specify other records also. The MX or Mail eXchange record tells mail servers how to route the email for the domain. Likewise TTL, SOA, etc.

3. Querying MX Record for Domain

Querying different types of DNS resource records only.

<strong># dig yahoo.com MX</strong>

; > DiG 9.16.1-Ubuntu > yahoo.com MX
;; global options:  cmd
;; Got answer:
;; ->>HEADER
<h4>4. Querying SOA Record for Domain</h4>
<pre class="brush:php;toolbar:false"><strong># dig yahoo.com SOA</strong>

; > DiG 9.16.1-Ubuntu > yahoo.com SOA
;; global options:  cmd
;; Got answer:
;; ->>HEADER
<h4>5. Querying TTL Record for Domain</h4>
<pre class="brush:php;toolbar:false"><strong># dig yahoo.com TTL</strong>

; > DiG 9.16.1-Ubuntu > yahoo.com TTL
;; global options:  cmd
;; Got answer:
;; ->>HEADER>HEADER
<h4>6. Querying Only Answer Section</h4>
<pre class="brush:php;toolbar:false"><strong># dig yahoo.com  nocomments  noquestion  noauthority  noadditional  nostats</strong>

; > DiG 9.16.1-Ubuntu > yahoo.com  nocomments  noquestion  noauthority  noadditional  nostats
;; global options:  cmd
yahoo.com.		1556	IN	A	74.6.231.20
yahoo.com.		1556	IN	A	98.137.11.163
yahoo.com.		1556	IN	A	98.137.11.164
yahoo.com.		1556	IN	A	74.6.143.26
yahoo.com.		1556	IN	A	74.6.231.21
yahoo.com.		1556	IN	A	74.6.143.25

7. Querying ALL DNS Records Types

<strong># dig yahoo.com ANY  noall  answer</strong>

; > DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 > yahoo.com ANY  noall  answer
;; global options:  cmd
yahoo.com.              3509    IN      A       72.30.38.140
yahoo.com.              3509    IN      A       98.138.253.109
yahoo.com.              3509    IN      A       98.139.183.24
yahoo.com.              1709    IN      MX      1 mta5.am0.yahoodns.net.
yahoo.com.              1709    IN      MX      1 mta6.am0.yahoodns.net.
yahoo.com.              1709    IN      MX      1 mta7.am0.yahoodns.net.
yahoo.com.              43109   IN      NS      ns2.yahoo.com.
yahoo.com.              43109   IN      NS      ns8.yahoo.com.
yahoo.com.              43109   IN      NS      ns3.yahoo.com.
yahoo.com.              43109   IN      NS      ns1.yahoo.com.
yahoo.com.              43109   IN      NS      ns4.yahoo.com.
yahoo.com.              43109   IN      NS      ns5.yahoo.com.
yahoo.com.              43109   IN      NS      ns6.yahoo.com.

8. DNS Reverse Look-up

Querying DNS Reverse Look-up. Only display answer section with using short.

<strong># dig -x 72.30.38.140  short</strong>

ir1.fp.vip.sp2.yahoo.com.

9. Querying Multiple DNS Records

Query multiple website’s DNS specific query viz. MX, NS, etc. records.

<strong># dig yahoo.com mx  noall  answer redhat.com ns  noall  answer</strong>

; > DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 > yahoo.com mx  noall  answer redhat.com ns  noall  answer
;; global options:  cmd
yahoo.com.              1740    IN      MX      1 mta6.am0.yahoodns.net.
yahoo.com.              1740    IN      MX      1 mta7.am0.yahoodns.net.
yahoo.com.              1740    IN      MX      1 mta5.am0.yahoodns.net.
redhat.com.             132     IN      NS      ns1.redhat.com.
redhat.com.             132     IN      NS      ns4.redhat.com.
redhat.com.             132     IN      NS      ns3.redhat.com.
redhat.com.             132     IN      NS      ns2.redhat.com.

10. Create .digrc file

Create .digrc file under $HOME/.digrc to store default dig options.

<strong># dig yahoo.com</strong>
yahoo.com.              3427    IN      A       72.30.38.140
yahoo.com.              3427    IN      A       98.138.253.109
yahoo.com.              3427    IN      A       98.139.183.24

We have store noall answer options permanently in the .digrc file under the user’s home directory. Now, whenever the dig command is executed it will show only answer section of the dig output. No Need to type every-time options like noall answer.

In this article, we tried to find out the dig command which may help you to search (DNS) Domain Name Service-related information. Share your thoughts through the comment box.

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