Command Line DNS Lookup with dig

dig is command line DNS Lookup program pre-installed on *nix and Macs. If you don’t have access to dig from the command line, there are some websites that offer a web interface to dig (e.g. Google Toolbox’s Online Dig).

Basic Lookup (Similar to ping)

dig example.com

Advantages over ping:

• Doesn’t get grumpy when you include http:// at the beginning
• Includes CNAME information if the lookup involves a CNAME record

Lookup Nameserver for a Specific URL

dig NS example.com

This generally returns something like

;; ANSWER SECTION:
example.com.        86400   IN  NS  a.iana-servers.net.
example.com.        86400   IN  NS  b.iana-servers.net.

Basic Lookup Using a Specific Nameserver

dig example.com @a.iana-servers.net

Where a.iana-servers.net is one of the nameservers returned when you queried with dig NS.

This is particularly useful when you want to confirm a new nameserver is properly configured before changing nameserver settings.

Lookup IPv6 Record

You can lookup a IPv6 record by requesting a AAAA record.

dig AAAA example.com

If a record exists, you’ll get a value like 2607:f8b0:4004:801::200e. For many domains, no AAAA record is set, in which case you will not get any value.

MX Records

dig MX example.com

Reverse DNS (lookup by IP)

dig -x 127.0.0.1

photo credit: FrodoBabbs via photopin cc