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How to Use Dig Command to Query DNS in Linux
Dig (Domain Information Groper) is a powerful command-line tool for querying DNS name servers.
With the dig command you can query information about various DNS records including host addresses, mail exchanges and name servers. It is the most commonly used tool among system administrators for troubleshooting DNS problems because of its flexibility and ease of use.
In this tutorial, we will show you how to use the dig utility through practical examples and detailed explanations of the most common dig options.
To check if the dig command is available on your system type:
The output should look something like this:
If the dig tool is not present on your system the command above will print
dig: command not found you can easily install it using the package manager of your distro.
Install Dig on Ubuntu and Debian
sudo apt install dnsutils
Install Dig on CentOS and Fedora
sudo yum install bind-utils
Understanding the Dig Output
In it’s simplest form when used to query a single host (domain) without any additional arguments, dig is pretty verbose.
In the following example we’ll perform a query to retrieve information about the
The output should look something like this:
Let’s go section by section and explain the output of the dig command:
The first line of the output prints the installed dig version, and the query that was invoked. The second line shows the global options (by default only cmd).
; <<>> DiG 9.13.3 <<>> linux.org ;; global options: +cmd
If you don’t want those lines to be included in the output use the
+nocmdoption. This options must be the very first argument after the dig command.
This section includes technical details about the answer received from the requested authority (DNS server). The first line of this section is the header, including the opcode (the action performed by dig) and the status of the action. In our case the status is
NOERRORwhich means that the requested authority served the query without any issue.
;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37159 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 5
This part of the output can be removed using the
+nocommentsoption. When this option is used it also disables some other sections headers.
This section is shown by default only on the newer versions if the dig utility. You can read more about the Extension mechanisms for DNS (EDNS) here.
;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096
If you don’t want this section to be included in the output use the
This is the section where dig shows our query (question). By default, dig will request the A record.
;; QUESTION SECTION: ;linux.org. IN A
You can disable this section using the
The answer section provide us with an answer to our question. As we already mentioned, by default dig will request the A record. In this case we can see that the domain
linux.orgpoints to the
;; ANSWER SECTION: linux.org. 300 IN A 126.96.36.199 linux.org. 300 IN A 188.8.131.52
Usually you do not want to turn off the answer, but you can remove this section from the output using the
The Authority section tell us what server(s) are the authority for answering DNS queries about the queried domain.
;; AUTHORITY SECTION: linux.org. 86379 IN NS lia.ns.cloudflare.com. linux.org. 86379 IN NS mark.ns.cloudflare.com.
You can disable this section of the output using the
The additional section give us information about the IP addresses of the authoritative DNS servers shown in the authority section.
;; ADDITIONAL SECTION: lia.ns.cloudflare.com. 84354 IN A 184.108.40.206 lia.ns.cloudflare.com. 170762 IN AAAA 2400:cb00:2049:1::adf5:3ab9 mark.ns.cloudflare.com. 170734 IN A 220.127.116.11 mark.ns.cloudflare.com. 170734 IN AAAA 2400:cb00:2049:1::adf5:3b82
This is the last section of the dig output which includes statistics about the query.
;; Query time: 58 msec ;; SERVER: 192.168.1.1#53(192.168.1.1) ;; WHEN: Fri Oct 12 11:46:46 CEST 2018 ;; MSG SIZE rcvd: 212
You can disable this part with the
Print Only the Answer
In most cases you would want to get only a quick answer to your dig query.
1. Get a Short Answer
To get a short answer to your query use the
dig linux.org +short
The output will include only the IP addresses of the A record.
2. Get a Detailed Answer
For more detailed answer turn off all the results using the
+noall options and then turn on only the answer section with the
dig linux.org +noall +answer
; <<>> DiG 9.13.3 <<>> linux.org +noall +answer ;; global options: +cmd linux.org. 67 IN A 18.104.22.168 linux.org. 67 IN A 22.214.171.124
Query Specific Name Server
By default if no name server is specified, dig will use the servers listed in
To specify a name server against which the query will be executed use the
@ (at) symbol followed by the name server IP address or hostname.
For example to query the Google name server (126.96.36.199) for information about the
linux.org domain you would use:
dig linux.org @188.8.131.52
; <<>> DiG 9.13.3 <<>> linux.org @184.108.40.206 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39110 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;linux.org. IN A ;; ANSWER SECTION: linux.org. 299 IN A 220.127.116.11 linux.org. 299 IN A 18.104.22.168 ;; Query time: 54 msec ;; SERVER: 22.214.171.124#53(126.96.36.199) ;; WHEN: Fri Oct 12 14:28:01 CEST 2018 ;; MSG SIZE rcvd: 70
Query a Record Type
Dig allows you to perform any valid DNS query by appending the record type to the end of the query. In the following section we will show you examples how to search for the most common records such as A (the IP address), CNAME ( canonical name) TXT (text record), MX (mail exchanger) and NS (name servers).
1. Querying A records
To get a list of all the address(es) for a domain name use the
dig +nocmd google.com a +noall +answer
google.com. 128 IN A 188.8.131.52
As you already know, if no DNS record type is specified dig will request the A record. You can also query the A record without specifying the
2. Querying CNAME records
To find the alias domain name use the
dig +nocmd mail.google.com cname +noall +answer
mail.google.com. 553482 IN CNAME googlemail.l.google.com.
3. Querying TXT records
txt option to retrieve all the TXT records for a specific domain:
dig +nocmd google.com txt +noall +answer
google.com. 300 IN TXT "facebook-domain-verification=22rm551cu4k0ab0bxsw536tlds4h95" google.com. 300 IN TXT "v=spf1 include:_spf.google.com ~all" google.com. 300 IN TXT "docusign=05958488-4752-4ef2-95eb-aa7ba8a3bd0e"
4. Querying MX records
To get a list of all the mail servers for a specific domain use the
dig +nocmd google.com mx +noall +answer
google.com. 494 IN MX 30 alt2.aspmx.l.google.com. google.com. 494 IN MX 10 aspmx.l.google.com. google.com. 494 IN MX 40 alt3.aspmx.l.google.com. google.com. 494 IN MX 50 alt4.aspmx.l.google.com. google.com. 494 IN MX 20 alt1.aspmx.l.google.com.
5. Querying NS records
To find the authoritative name servers for our specific domain use the
dig +nocmd google.com ns +noall +answer
google.com. 84527 IN NS ns1.google.com. google.com. 84527 IN NS ns2.google.com. google.com. 84527 IN NS ns4.google.com. google.com. 84527 IN NS ns3.google.com.
6. Querying All Records
any option to get a list of all DNS records for a specific domain:
dig +nocmd google.com any +noall +answer
google.com. 299 IN A 184.108.40.206 google.com. 299 IN AAAA 2a00:1450:4017:804::200e google.com. 21599 IN NS ns2.google.com. google.com. 21599 IN NS ns1.google.com. google.com. 599 IN MX 30 alt2.aspmx.l.google.com. google.com. 21599 IN NS ns4.google.com. google.com. 599 IN MX 50 alt4.aspmx.l.google.com. google.com. 599 IN MX 20 alt1.aspmx.l.google.com. google.com. 299 IN TXT "docusign=05958488-4752-4ef2-95eb-aa7ba8a3bd0e" google.com. 21599 IN CAA 0 issue "pki.goog" google.com. 599 IN MX 40 alt3.aspmx.l.google.com. google.com. 3599 IN TXT "facebook-domain-verification=22rm551cu4k0ab0bxsw536tlds4h95" google.com. 21599 IN NS ns3.google.com. google.com. 599 IN MX 10 aspmx.l.google.com. google.com. 3599 IN TXT "v=spf1 include:_spf.google.com ~all" google.com. 59 IN SOA ns1.google.com. dns-admin.google.com. 216967258 900 900 1800 60
Reverse DNS Lookup
To query the hostname associated with a specific IP address use the
For example to perform a reverse lookup on
220.127.116.11 you would use:
dig -x 18.104.22.168 +noall +answer
As you can see from the output below the IP address
22.214.171.124 is associated with the hostname
; <<>> DiG 9.13.3 <<>> -x 126.96.36.199 +noall +answer ;; global options: +cmd 188.8.131.52.in-addr.arpa. 245 IN PTR wildebeest.gnu.org.
If you want to query a large number of domains, you can add the them in a file (one domain per line) and use the
-f option followed by the file name.
In the following example we are querying the domains listed in the
lxer.com linuxtoday.com tuxmachines.org
dig -f domains.txt +short
184.108.40.206 220.127.116.11 18.104.22.168
The .digrc File
The dig command’s behavior can be controlled by setting up per user options in the
.digrc file is present in the user’s home directory, the options specified in it are applied before the command line arguments.
For example if you want to display only the answer section, open your text editor and create the following
+nocmd +noall +answer
By now you should have a good understanding of how to use the Linux dig command and you should be able to troubleshoot most of the DNS related issues.