whois and dig Commands

whoisThe whois Command

The whois command is useful when trying to track down a contact for someone causing trouble on your network. This command queries the primary domain name servers and returns all the information that Internic (or whoever their name registrar is) has. Internic used to be the quasi-government agency that was responsible for keeping track of all the domain names on the Internet. Internic became a commercial company called Network Solutions, and was then acquired by VeriSign. Now that name registration has been opened up for competition, there are literally dozens of official name registrars. However, you can still usually find out who owns a domain by using the whois command.

This command is useful for attacks coming both from within companies or within ISP networks. Either way, you can track down the person responsible for that network and report your problems to them. They won’t always be helpful, but at least you can try. The syntax is:

whois domain-name.com

The variable domain-name.com is the domain name on which you are looking for information.

As an example, here’s the whois information for linux.com:

Domain Name: LINUX.COM
Registry Domain ID:
Registrar WHOIS Server: whois.domain.com
Registrar URL: www.domain.com
Updated Date: 2013-05-08 13:51:05
Creation Date: 1994-06-02 04:00:00
Registrar Registration Expiration Date: 2016-06-01 04:00:00
Registrar: Domain.com, LLC
Registrar IANA ID: 886
Registrar Abuse Contact Email: compliance@domain-inc.net
Registrar Abuse Contact Phone: +1.6027165396
Reseller: Dotster.com
Reseller: support@dotster-inc.com
Reseller: +1.8004015250
Domain Status: clientTransferProhibited
Domain Status: clientUpdateProhibited
Registry Registrant ID:
Registrant Name: Jim Zemlin
Registrant Organization: The Linux Foundation
Registrant Street: 660 York Street Suite 102
Registrant City: San Francisco
Registrant State/Province: CA
Registrant Postal Code: 94110
Registrant Country: US
Registrant Phone: +1.4157239709
Registrant Phone Ext:
Registrant Fax: +1.4157239709
Registrant Fax Ext:
Registrant Email: admin@linux-foundation.org
Registry Admin ID:
Admin Name: Jim Zemlin
Admin Organization: The Linux Foundation
Admin Street: 660 York Street Suite 102
Admin City: San Francisco
Admin State/Province: CA
Admin Postal Code: 94110
Admin Country: US
Admin Phone: +1.4157239709
Admin Phone Ext:
Admin Fax: +1.4157239709
Admin Fax Ext:
Admin Email: admin@linux-foundation.org
Registry Tech ID:
Tech Name: Jim Zemlin
Tech Organization: The Linux Foundation
Tech Street: 660 York Street Suite 102
Tech City: San Francisco
Tech State/Province: CA
Tech Postal Code: 94110
Tech Country: US
Tech Phone: +1.4157239709
Tech Phone Ext:
Tech Fax: +1.4157239709
Tech Fax Ext:
Tech Email: admin@linux-foundation.org
Name Server: NS1.LINUX-FOUNDATION.NET
Name Server: NS2.LINUX-FOUNDATION.NET
DNSSEC: Unsigned
URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/
>>> Last update of WHOIS database: 2013-05-08 13:51:05 <<<

Registration Service Provider:
Dotster.com, support@dotster-inc.com
+1.8004015250
This company may be contacted for domain login/passwords,
DNS/Nameserver changes, and general domain support questions.

As you can see, you can contact the technical person in charge of that domain directly. If that doesn’t work, you can always try the administrative person. The whois command usually displays an e-mail address, a mailing address, and sometimes phone numbers. It tells when the domain was created and if they’ve made recent changes to their whois listing. It also shows the domain name servers responsible for that domain name. Querying these numbers with the dig command can generate even more information about the remote network’s configuration.


Unfortunately, whois is not built into the Windows platforms, but there are plenty of web-based whois engines, including the one located on Network Solutions web site.

It should be noted that if you administer domains of your own, you should make sure your whois listing is both up-to-date and as generic as possible. Putting real e-mail addresses and names in the contact information fields gives information that an outsider can use either for social engineering or password-cracking attacks. Also, people might leave the company, making your record outdated. It is better to use generic e-mail addresses, such as dnsmaster@example.com or admin@example.com. You can forward these e-mails to the people responsible, and it doesn’t give out valuable information on your technical organization structure.

The dig Command

The dig command queries a name server for certain information about a domain. Dig is an updated version of the nslookup command, which had be depricated (but has since been revived). You can see it to determine the machine names used on a network, what the IP addresses tied to those machines are, which one is their mail server, and other useful tidbits of information. The general syntax is:

dig @server domain type

where server is the DNS server you want to query, domain is the domain you are asking about, and type is the kind of information you want on it. You will generally want to query the authoritative DNS for that domain: that is, te one listed in their whois record as being the final authority on that domain. Sometimes the company runs this server; other times its ISP runs the server.

Results of the dig command can yield valuable information, such as the host name of their mail server, their DNS server, and other important machines on their network. If you run a DNS server, you should be able to configure it to respond only to these kinds from authorized machines.

dig Record Types

Options Descriptions
AXFR Attempts to get the whole file for the domain or “zone” file. Some servers are now configured not to allow zone file transfers, so you may have to ask for specific records.
A Returns any “A” records. “A” records are individual host names on the network, such as webserver.example.com and firewall1.example.com.
MX Returns the registered mail host name for that domain. This is useful if you want to contact an administrator (try administrator@mailhost.example.com or root@mailhost.example.com).
CNAME Returns any CNAMED hosts, also known as aliases. For example: fido.example.com = www.example.com.
ANY Returns any information it can generate on the domain. Sometimes this works when AXFR doesn’t

External Links:

The whois protocol at Wikipedia

The dig command at Wikipedia

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