dig is a network administration command-line tool for querying the Domain Name System (DNS).
dig is useful for network troubleshooting and for educational purposes. It can operate based on command line option and flag arguments, or in batch mode by reading requests from an operating system file. When a specific name server is not specified in the command invocation, it uses the operating system's default resolver, usually configured in the file resolv.conf. Without any arguments it queries the DNS root zone.
dig supports Internationalized domain name (IDN) queries.
dig is a component of the domain name server software suite BIND. dig supersedes in functionality older tools, such as nslookup and the program host; however, the older tools are still used in complementary fashion.
Example usage
In this example, dig is used to query for any-type of record information in the domain example.com:
$ dig example.com any ; <<>> DiG 9.6.1 <<>> example.com any ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4016 ;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;example.com. IN ANY ;; ANSWER SECTION: example.com. 172719 IN NS a.iana-servers.net. example.com. 172719 IN NS b.iana-servers.net. example.com. 172719 IN A 208.77.188.166 example.com. 172719 IN SOA dns1.icann.org. hostmaster.icann.org. 2007051703 7200 3600 1209600 86400 ;; Query time: 1 msec ;; SERVER: ::1#53(::1) ;; WHEN: Wed Aug 12 11:40:43 2009 ;; MSG SIZE rcvd: 154
The number 172719 in the above example is the time to live value, which indicates the time of validity of the data.
Queries may be directed to designated DNS servers for specific records; in this example, MX records:
$ dig wikimedia.org MX @ns0.wikimedia.org ; <<>> DiG 9.6.1 <<>> wikimedia.org MX @ns0.wikimedia.org ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61144 ;; flags: qr aa rd; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;wikimedia.org. IN MX ;; ANSWER SECTION: wikimedia.org. 3600 IN MX 10 mchenry.wikimedia.org. wikimedia.org. 3600 IN MX 50 lists.wikimedia.org. ;; ADDITIONAL SECTION: mchenry.wikimedia.org. 3600 IN A 208.80.152.186 lists.wikimedia.org. 3600 IN A 91.198.174.5 ;; Query time: 73 msec ;; SERVER: 208.80.152.130#53(208.80.152.130) ;; WHEN: Wed Aug 12 11:51:03 2009 ;; MSG SIZE rcvd: 109
History
dig was originally written by Steve Hotz and incorporated into BIND 4; later it was rewritten by Michael Sawyer, and is maintained by the Internet Systems Consortium as part of BIND 9.
When originally written, the manual page for dig indicated that its name was an acronym for "Domain Information Groper". This expansion was removed in 2017; the tool's name is now simply "dig".
See also
- BIND name server
- Root name server - top-level name servers providing top level domain name resolution
- List of DNS record types - possible types of records stored and queried within DNS
- whois
References
Bibliography
- Paul Albitz and Cricket Liu. DNS and BIND, 5th Edition. Nutshell Series. O'Reilly and Associates, Inc., 2006.