H-6. nslookup and dignslookup, found on Unix and Windows systems, is used to get IP address information on a host, and vice versa: C:\>nslookup www.yahoo.com Server: ns1.mindspring.com Address: 207.69.188.185 Non-authoritative answer: Name: www.yahoo.akadns.net Addresses: 216.109.118.75, 216.109.118.77, 216.109.118.78, 216.109.118.79 216.109.118.65, 216.109.118.66, 216.109.118.69, 216.109.118.73 Aliases: www.yahoo.com C:\>nslookup 216.109.118.75 Server: ns1.mindspring.com Address: 207.69.188.185 Name: p12.www.dcn.yahoo.com Address: 216.109.118.75 While nslookup has been widely used on Unix systems for many, many years, nslookup is being deprecated on Linux systems. Instead of nslookup, Linux systems now make use of a command called dig (dig stands for Domain Internet Groper). Let's look at some example usage of dig: $ dig @69.15.40.52 www.yahoo.com ; <<>> DiG 9.2.4 <<>> @69.15.40.52 www.yahoo.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7406 ;; flags: qr rd ra; QUERY: 1, ANSWER: 9, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;www.yahoo.com. IN A ;; ANSWER SECTION: www.yahoo.com. 300 IN CNAME www.yahoo.akadns.net. www.yahoo.akadns.net. 60 IN A 68.142.226.34 www.yahoo.akadns.net. 60 IN A 68.142.226.56 www.yahoo.akadns.net. 60 IN A 68.142.226.44 www.yahoo.akadns.net. 60 IN A 68.142.226.45 www.yahoo.akadns.net. 60 IN A 68.142.226.38 www.yahoo.akadns.net. 60 IN A 68.142.226.47 www.yahoo.akadns.net. 60 IN A 68.142.226.39 www.yahoo.akadns.net. 60 IN A 68.142.226.43 ;; Query time: 239 msec ;; SERVER: 69.15.40.52#53(69.15.40.52) ;; WHEN: Mon May 16 08:13:18 2005 ;; MSG SIZE rcvd: 193 $ The @ value is optional. You could use a domain name or, as we did, an IP address. It specifies the name server to be queried. The second option is the host we want to look up. Using the -x option with dig, you can get reverse name lookup: $ dig -x 68.142.226.34 ; <<>> DiG 9.2.4 <<>> -x 68.142.226.34 ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 51297 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;34.226.142.68.in-addr.arpa. IN PTR ;; ANSWER SECTION: 34.226.142.68.in-addr.arpa. 1200 IN PTR p3.www.re2.yahoo.com. ;; Query time: 79 msec ;; SERVER: 69.15.40.52#53(69.15.40.52) ;; WHEN: Mon May 16 08:13:47 2005 ;; MSG SIZE rcvd: 78 With the mx option, dig can be used to obtain the mail exchanger information for a domain: $ dig mx yahoo.com ; <<>> DiG 9.2.4 <<>> mx yahoo.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25 ;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;yahoo.com. IN MX ;; ANSWER SECTION: yahoo.com. 6557 IN MX 1 mx3.mail.yahoo.com. yahoo.com. 6557 IN MX 5 mx4.mail.yahoo.com. yahoo.com. 6557 IN MX 1 mx1.mail.yahoo.com. yahoo.com. 6557 IN MX 1 mx2.mail.yahoo.com. ;; Query time: 1 msec ;; SERVER: 69.15.40.52#53(69.15.40.52) ;; WHEN: Mon May 16 08:14:26 2005 ;; MSG SIZE rcvd: 112 The soa option can be used to obtain zone authority information: $ dig soa yahoo.com ; <<>> DiG 9.2.4 <<>> soa yahoo.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41407 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;yahoo.com. IN SOA ;; ANSWER SECTION: yahoo.com. 1800 IN SOA ns1.yahoo.com. hostmaster.yahoo-inc.com. 2005051609 3600 300 604800 600 ;; Query time: 21 msec ;; SERVER: 69.15.40.52#53(69.15.40.52) ;; WHEN: Mon May 16 08:14:45 2005 ;; MSG SIZE rcvd: 88 See the manual page for more details on this powerful tool. |