dig Command in Linux with Examples
dig command stands for Domain Information Groper. It retrieves information about DNS name servers. Network administrators use it to verify and troubleshoot DNS problems and perform DNS lookups. The dignslookup and the host.
Installing Dig command
In case of Debian/Ubuntu
$sudo apt-get install dnsutils
In case of CentOS/RedHat
$sudo yum install bind-utils
Syntax:
dig [server] [name] [type]
Working with Dig Command
1. To query domain “A” record
dig geeksforgeeks.org
This command causes dig to look up the “A” record for the domain name “geeksforgeeks.org”.
A record refers to IPV4 IP.
Similarly, if record type is set as “AAAA”, this would return IPV6 IP.
2. To query domain “A” record with +short
dig geeksforgeeks.org +short
By default dig is verbose and by using “+short” option we can reduce the output drastically as shown. 3. To remove comment lines.
dig geeksforgeeks.org +nocomments
This command makes a request and excludes the comment lines. 4. To set or clear all display flags.
dig geeksforgeeks.org +noall
We use the “noall” query option, when we want to set or clear all display flags. 5. To query detailed answers.
dig geeksforgeeks.org +noall +answer
If we want to view the answers section information in detail, we first stop the display of all section using “+noall” option and then query the answers section only by using “+answer” option with the dig command. 6. To query all DNS record types.
dig geeksforgeeks.org ANY
We use “ANY” option to query all the available DNS record types associated with a domain. It will include all the available record types in the output. 7. To query MX record for the domain.
dig geeksforgeeks.org MX
If we want only the mail exchange – MX – answer section associated with a domain we use this command. 8. To trace DNS path
dig geeksforgeeks.org +trace
“+trace” command is used for tracing the DNS lookup path. This option makes iterative queries to resolve the name lookup. It will query the name servers starting from the root and subsequently traverses down the namespace tree using iterative queries following referrals along the way. 9. For specifying name servers
dig geeksforgeeks.org @8.8.8.8
By default, dig command will query the name servers listed in “/etc/resolv.conf” to perform a DNS lookup. We can change it by using @ symbol followed by a hostname or IP address of the name server. 10. To query the statistics section
dig geeksforgeeks.org +noall +answer +stats
We use “+stats” option with dig command, to see the statistics section.
Reverse DNS Lookup
Reverse DNS lookup can be used to fetch domain name or the host name from the IP address.
“-x” option is used to perform reverse DNS lookup.
ex:
[xxxxxx ~]# dig +noall +answer -x 8.8.8.8
8.8.8.8.in-addr.arpa. 18208 IN PTR dns.google.
Note: DNS reverse look up will work only if the entry is present PTR.
PTR contents can be viewed using the command "dig -x xx.yy.zz.aa"
Batch Queries
Instead performing dig query for each domain at a time, a list of domains can be queried at once. To do so, enter the domain names in a file, only 1 domain name in each line and perform the dig query on file.
ex: let’s say, file.txt has the list of domain names to be queried then,
dig -f file.txt +shortwill perform DNS queries and return all the resolved IPs.
Conclusion
The dig (Domain Information Groper) command in Linux is a powerful tool used for querying DNS (Domain Name Sysetm) servers troubleshooting network-relatd issues. It provides detailed information about DNS records, including types like A, AAAA, MX, NS, CNAME, and TXT records, making it invaluable for network administrators and developers. dig is especially helpful for verifying DNS records, ensuring that domain configuration are accurate and DNS propagation is complete.
dig Command in Linux – FAQs
What is the purpose of the dig command in Linux?
The dig command is used to perform DNS lookups. It helps in retrieving information such as IP addresses associated with domain names, mail servers, name servers, and more DNS records.
What does the dig command stand for?
dig stands for Domain Information Gropper. It’s tool for querying DNS servers to get information about domain names and their associated IP addresses.
Can I use dig to look up IPv6 addresses?
Yes, use the AAAA record type for IPv6.
dig example.com AAAA
What does “Query time” mean in the dig output?
The “Query time:” indicates how long (in milliseconds) it took for the DNS query to complete.
