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17.2.4. Using the dig Utility
The
dig utility is a command-line tool that allows you to perform DNS lookups and debug a nameserver configuration. Its typical usage is as follows:
dig [@server] [option...] name type
See Section 17.2.2.2, “Common Resource Records” for a list of common types.
17.2.4.1. Looking Up a Nameserver
To look up a nameserver for a particular domain, use the command in the following form:
dig name NS
In Example 17.17, “A sample nameserver lookup”, the
dig utility is used to display nameservers for example.com.
Example 17.17. A sample nameserver lookup
~]$ dig example.com NS
; <<>> DiG 9.7.1-P2-RedHat-9.7.1-2.P2.fc13 <<>> example.com NS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57883
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;example.com. IN NS
;; ANSWER SECTION:
example.com. 99374 IN NS a.iana-servers.net.
example.com. 99374 IN NS b.iana-servers.net.
;; Query time: 1 msec
;; SERVER: 10.34.255.7#53(10.34.255.7)
;; WHEN: Wed Aug 18 18:04:06 2010
;; MSG SIZE rcvd: 7717.2.4.2. Looking Up an IP Address
To look up an IP address assigned to a particular domain, use the command in the following form:
dig name A
In Example 17.18, “A sample IP address lookup”, the
dig utility is used to display the IP address of example.com.
Example 17.18. A sample IP address lookup
~]$ dig example.com A
; <<>> DiG 9.7.1-P2-RedHat-9.7.1-2.P2.fc13 <<>> example.com A
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4849
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0
;; QUESTION SECTION:
;example.com. IN A
;; ANSWER SECTION:
example.com. 155606 IN A 192.0.32.10
;; AUTHORITY SECTION:
example.com. 99175 IN NS a.iana-servers.net.
example.com. 99175 IN NS b.iana-servers.net.
;; Query time: 1 msec
;; SERVER: 10.34.255.7#53(10.34.255.7)
;; WHEN: Wed Aug 18 18:07:25 2010
;; MSG SIZE rcvd: 9317.2.4.3. Looking Up a Hostname
To look up a host name for a particular IP address, use the command in the following form:
dig-xaddress
In Example 17.19, “A sample host name lookup”, the
dig utility is used to display the host name assigned to 192.0.32.10.
Example 17.19. A sample host name lookup
~]$ dig -x 192.0.32.10
; <<>> DiG 9.7.1-P2-RedHat-9.7.1-2.P2.fc13 <<>> -x 192.0.32.10
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29683
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 6
;; QUESTION SECTION:
;10.32.0.192.in-addr.arpa. IN PTR
;; ANSWER SECTION:
10.32.0.192.in-addr.arpa. 21600 IN PTR www.example.com.
;; AUTHORITY SECTION:
32.0.192.in-addr.arpa. 21600 IN NS b.iana-servers.org.
32.0.192.in-addr.arpa. 21600 IN NS c.iana-servers.net.
32.0.192.in-addr.arpa. 21600 IN NS d.iana-servers.net.
32.0.192.in-addr.arpa. 21600 IN NS ns.icann.org.
32.0.192.in-addr.arpa. 21600 IN NS a.iana-servers.net.
;; ADDITIONAL SECTION:
a.iana-servers.net. 13688 IN A 192.0.34.43
b.iana-servers.org. 5844 IN A 193.0.0.236
b.iana-servers.org. 5844 IN AAAA 2001:610:240:2::c100:ec
c.iana-servers.net. 12173 IN A 139.91.1.10
c.iana-servers.net. 12173 IN AAAA 2001:648:2c30::1:10
ns.icann.org. 12884 IN A 192.0.34.126
;; Query time: 156 msec
;; SERVER: 10.34.255.7#53(10.34.255.7)
;; WHEN: Wed Aug 18 18:25:15 2010
;; MSG SIZE rcvd: 310